ICN2 Publications


  • A label-free nanostructured plasmonic biosensor based on Blu-ray discs with integrated microfluidics for sensitive biodetection

    López-Muñoz G.A., Estevez M.-C., Peláez-Gutierrez E.C., Homs-Corbera A., García-Hernandez M.C., Imbaud J.I., Lechuga L.M. Biosensors and Bioelectronics; 96: 260 - 267. 2017. 10.1016/j.bios.2017.05.020.

    NanoBiosensors and Bioanalytical Applications

    Nanostructure-based plasmonic biosensors have quickly positioned themselves as interesting candidates for the design of portable optical biosensor platforms considering the potential benefits they can offer in integration, miniaturization, multiplexing, and real-time label-free detection. We have developed a simple integrated nanoplasmonic sensor taking advantage of the periodic nanostructured array of commercial Blu-ray discs. Sensors with two gold film thicknesses (50 and 100 nm) were fabricated and optically characterized by varying the oblique-angle of the incident light in optical reflectance measurements. Contrary to the use normal light incidence previously reported with other optical discs, we observed an enhancement in sensitivity and a narrowing of the resonant linewidths as the light incidence angle was increased, which could be related to the generation of Fano resonant modes. The new sensors achieve a figure of merit (FOM) up to 35 RIU−1 and a competitive bulk limit of detection (LOD) of 6.3×10−6 RIU. These values significantly improve previously reported results obtained with normal light incidence reflectance measurements using similar structures. The sensor has been combined with versatile, simple, ease to-fabricate microfluidics. The integrated chip is only 1 cm2 (including a PDMS flow cell with a 50 µm height microfluidic channel fabricated with double-sided adhesive tape) and all the optical components are mounted on a 10 cm×10 cm portable prototype, illustrating its facile miniaturization, integration and potential portability. Finally, to assess the label-free biosensing capability of the new sensor, we have evaluated the presence of specific antibodies against the GTF2b protein, a tumor-associate antigen (TAA) related to colorectal cancer. We have achieved a LOD in the pM order and have assessed the feasibility of directly measuring biological samples such as human serum. © 2017 Elsevier B.V.

  • A statistical analysis of nanocavities replication applied to injection moulding

    Pina-Estany J., Colominas C., Fraxedas J., Llobet J., Perez-Murano F., Puigoriol-Forcada J.M., Ruso D., Garcia-Granada A.A. International Communications in Heat and Mass Transfer; 81: 131 - 140. 2017. 10.1016/j.icheatmasstransfer.2016.11.003.

    Force Probe Microscopy and Surface Nanoengineering

    The purpose of this paper is to investigate both theoretically and experimentally how nanocavities are replicated in the injection moulding manufacturing process. The objective is to obtain a methodology for efficiently replicate nanocavities. From the theoretical point of view, simulations are carried out using a submodeling approach combining Solidworks Plastics for a first macrosimulation and Fluent solver for a subsequent nanosimulation. The effect of the four main factors (melt temperature, mould temperature, filling time and cavity geometry) are quantified using an statistical 24 factorial experiment. It is found that the main effects are the cavity length, the mould temperature and the polymer temperature, with standardized effects of 5, 3 and 2.6, respectively. Filling time has a negative 1.3 standardized effect. From the experimental point of view, Focused Ion Beam technique is used for mechanizing nanocavities in a steel mould. The replication achieved in polycarbonate injection is quantified using an Atomic Force Microscope. It is observed how both the geometry and the position of the cavities in the mould affect its replication. © 2016 Elsevier Ltd

  • A universal strategy for metal oxide anchored and binder-free carbon matrix electrode: A supercapacitor case with superior rate performance and high mass loading

    Zhang X., Luo J., Tang P., Ye X., Peng X., Tang H., Sun S.-G., Fransaer J. Nano Energy; 31: 311 - 321. 2017. 10.1016/j.nanoen.2016.11.024.

    Despite the significant advances in preparing carbon-metal oxide composite electrodes, strategies for seamless interconnecting of these two materials without using binders are still scarce. Herein we design a novel method for in situ synthesis of porous 2D-layered carbon–metal oxide composite electrode. Firstly, 2D-layered Ni-Co mixed metal-organic frameworks (MOFs) are deposited directly on nickel foam by anodic electrodeposition. Subsequent pyrolysis and activation procedure lead to the formation of carbon–metal oxides composite electrodes. Even with an ultrahigh mass loading of 13.4 mg cm−2, the as-prepared electrodes exhibit a superior rate performance of 93% (from 1 to 20 mA cm−2), high capacitance (2098 mF cm−2 at a current density of 1 mA cm−2), low resistance and excellent cycling stability, making them promising candidates for practical supercapacitor application. As a proof of concept, several MOF derived electrodes with different metal sources have also been prepared successfully via the same route, demonstrating the versatility of the proposed method for the preparation of binder-free carbon–metal oxide composite electrodes for electrochemical devices. © 2016 Elsevier Ltd

  • Ab initio study of electron-phonon coupling in rubrene

    Ordejón P., Boskovic D., Panhans M., Ortmann F. Physical Review B; 96 (3, 035202) 2017. 10.1103/PhysRevB.96.035202.

    Theory and Simulation

    The use of ab initio methods for accurate simulations of electronic, phononic, and electron-phonon properties of molecular materials such as organic crystals is a challenge that is often tackled stepwise based on molecular properties calculated in gas phase and perturbatively treated parameters relevant for solid phases. In contrast, in this work we report a full first-principles description of such properties for the prototypical rubrene crystals. More specifically, we determine a Holstein-Peierls-type Hamiltonian for rubrene, including local and nonlocal electron-phonon couplings. Thereby, a recipe for circumventing the issue of numerical inaccuracies with low-frequency phonons is presented. In addition, we study the phenyl group motion with a molecular dynamics approach. © 2017 American Physical Society.

  • An automated optofluidic biosensor platform combining interferometric sensors and injection moulded microfluidics

    Szydzik C., Gavela A.F., Herranz S., Roccisano J., Knoerzer M., Thurgood P., Khoshmanesh K., Mitchell A., Lechuga L.M. Lab on a Chip; 17 (16): 2793 - 2804. 2017. 10.1039/c7lc00524e.

    NanoBiosensors and Bioanalytical Applications

    A primary limitation preventing practical implementation of photonic biosensors within point-of-care platforms is their integration with fluidic automation subsystems. For most diagnostic applications, photonic biosensors require complex fluid handling protocols; this is especially prominent in the case of competitive immunoassays, commonly used for detection of low-concentration, low-molecular weight biomarkers. For this reason, complex automated microfluidic systems are needed to realise the full point-of-care potential of photonic biosensors. To fulfil this requirement, we propose an on-chip valve-based microfluidic automation module, capable of automating such complex fluid handling. This module is realised through application of a PDMS injection moulding fabrication technique, recently described in our previous work, which enables practical fabrication of normally closed pneumatically actuated elastomeric valves. In this work, these valves are configured to achieve multiplexed reagent addressing for an on-chip diaphragm pump, providing the sample and reagent processing capabilities required for automation of cyclic competitive immunoassays. Application of this technique simplifies fabrication and introduces the potential for mass production, bringing point-of-care integration of complex automated microfluidics into the realm of practicality. This module is integrated with a highly sensitive, label-free bimodal waveguide photonic biosensor, and is demonstrated in the context of a proof-of-concept biosensing assay, detecting the low-molecular weight antibiotic tetracycline. © 2017 The Royal Society of Chemistry.

  • Analysis of alternative splicing events for cancer diagnosis using a multiplexing nanophotonic biosensor

    Huertas C.S., Domínguez-Zotes S., Lechuga L.M. Scientific Reports; 7 ( 41368) 2017. 10.1038/srep41368.

    NanoBiosensors and Bioanalytical Applications

    Personalized medicine is a promising tool not only for prevention, screening and development of more efficient treatment strategies, but also for diminishing the side effects caused by current therapies. Deciphering gene regulation pathways provides a reliable prognostic analysis to elucidate the origin of grave diseases and facilitate the selection of the most adequate treatment for each individual. Alternative splicing of mRNA precursors is one of these gene regulation pathways and enables cells to generate different protein outputs from the same gene depending on their developmental or homeostatic status. Its deregulation is strongly linked to disease onset and progression constituting a relevant and innovative class of biomarker. Herein we report a highly selective and sensitive nanophotonic biosensor based on the direct monitoring of the aberrant alternative splicing of Fas gene. Unlike conventional methods, the nanobiosensor performs a real-time detection of the specific isoforms in the fM-pM range without any cDNA synthesis or PCR amplification requirements. The nanobiosensor has been proven isoform-specific with no crosshybridization, greatly minimizing detection biases. The demonstrated high sensitivity and specificity make our nanobiosensor ideal for examining significant tumor-associated expression shifts of alternatively spliced isoforms for the early and accurate theranostics of cancer.

  • Analysis of C9orf72 repeat expansions in a large international cohort of dementia with Lewy bodies

    Kun-Rodrigues C., Ross O.A., Orme T., Shepherd C., Parkkinen L., Darwent L., Hernandez D., Ansorge O., Clark L.N., Honig L.S., Marder K., Lemstra A., Scheltens P., van der Flier W., Louwersheimer E., Holstege H., Rogaeva E., St. George-Hyslop P., Londos E., Zetterberg H., Barber I., Braae A., Brown K., Morgan K., Maetzler W., Berg D., Troakes C., Al-Sarraj S., Lashley T., Holton J., Compta Y., Van Deerlin V., Trojanowski J.Q., Serrano G.E., Beach T.G., Clarimon J., Lleó A., Morenas-Rodríguez E., Lesage S., Galasko D., Masliah E., Santana I., Diez M., Pastor P., Tienari P.J., Myllykangas L., Oinas M., Revesz T., Lees A., Boeve B.F., Petersen R.C., Ferman T.J., Escott-Price V., Graff-Radford N., Cairns N.J., Morris J.C., Stone D.J., Pickering-Brown S., Mann D., Dickson D.W., Halliday G.M., Singleton A., Guerreiro R., Bras J. Neurobiology of Aging; 49: 214.e13 - 214.e15. 2017. 10.1016/j.neurobiolaging.2016.08.023.

    C9orf72 repeat expansions are a common cause of amyotrophic lateral sclerosis and frontotemporal dementia. To date, no large-scale study of dementia with Lewy bodies (DLB) has been undertaken to assess the role of C9orf72 repeat expansions in the disease. Here, we investigated the prevalence of C9orf72 repeat expansions in a large cohort of DLB cases and identified no pathogenic repeat expansions in neuropathologically or clinically defined cases, showing that C9orf72 repeat expansions are not causally associated with DLB. © 2016 Elsevier Inc.

  • Angle-Dependent Photoluminescence Spectroscopy of Solution-Processed Organic Semiconducting Nanobelts

    Wang M., Gong Y., Alzina F., Sotomayor Torres C.M., Li H., Zhang Z., He J. Journal of Physical Chemistry C; 121 (22): 12441 - 12446. 2017. 10.1021/acs.jpcc.7b02958.

    Phononic and Photonic Nanostructures

    We report an anomalous anisotropy in photoluminescence (PL) from crystalline nanobelt of an organic small-molecule semiconductor, 6,13-dichloropentacene (DCP). Large-area well-aligned DCP nanobelt arrays are readily formed by self-assembly through solution method utilizing the strong anisotropic interactions between molecules. The absorption spectrum of the arrays suggests the formation of both intramolecular exciton and intermolecular exciton. However, the results of angle-dependent PL spectroscopy indicate that the PL arises only from the relaxation of intramolecular exciton, which has an optical transition dipole moment with an angle of 115° with the long-axis of the nanobelts. The angular dependence of PL signals follows a quartic rule (IPL(θ) ∞ cos4(θ - 115)) and agrees well with the optical selection rule of individual DCP molecules. The measured polarization ratio ρ from the individual nanobelts is on average 0.91 ± 0.02, superior to that of prior-art organic semiconductors. These results provide new insights into exciton behavior in 1D π-π stacking organic semiconductors and demonstrate DCP's great potential in the photodetectors and optical switches for large-scale organic optoelectronics. © 2017 American Chemical Society.

  • Anisotropic features in the electronic structure of the two-dimensional transition metal trichalcogenide TiS3: Electron doping and plasmons

    Silva-Guillén J.A., Canadell E., Ordejón P., Guinea F., Roldán R. 2D Materials; 4 (2, 025085) 2017. 10.1088/2053-1583/aa6b92.

    Theory and Simulation

    Analysis of the band structure of TiS3 single-layers suggests the possibility of changing their physical behaviour by injecting electron carriers. The anisotropy of the valence and conduction bands is explained in terms of their complex orbital composition. The nature of the Fermi surface and Lindhard response function for different doping concentrations is studied by means of firstprinciples DFT calculations. It is suggested that for electron doping levels x (number of electrons per unit cell) ~0.18-0.30e- the system could exhibit incommensurate charge or spin modulations which, however, would keep the metallic state whereas systems doped with smaller x would be 2D metals without any electronic instability. The effect of spin-orbit coupling in the band dispersion is analysed. The DFT effective masses are used to study the plasmon spectrum from an effective low energy model. We find that this material supports highly anisotropic plasmons, with opposite anisotropy for the electron and hole bands.

  • Assembly of Plasmonic Nanoparticles on Nanopatterns of Polymer Brushes Fabricated by Electrospin Nanolithography

    Kiremitler N.B., Pekdemir S., Patarroyo J., Karabel S., Torun I., Puntes V.F., Onses M.S. ACS Macro Letters; 6 (6): 603 - 608. 2017. 10.1021/acsmacrolett.7b00288.

    Inorganic Nanoparticles

    This paper presents electrospin nanolithography (ESPNL) for versatile and low-cost fabrication of nanoscale patterns of polymer brushes to serve as templates for assembly of metallic nanoparticles. Here electrospun nanofibers placed on top of a substrate grafted with polymer brushes serve as masks. The oxygen plasma etching of the substrate followed by removal of the fibers leads to linear patterns of polymer brushes. The line-widths as small as ∼50 nm can be achieved by precise tuning of the diameter of fibers, etching condition, and fiber-substrate interaction. Highly aligned and spatially defined patterns can be fabricated by operating in the near-field electrospinning regime. Patterns of polymer brushes with two different chemistries effectively directed the assembly of gold nanoparticles and silver nanocubes. Nanopatterned brushes imparted strong confinement effects on the assembly of plasmonic nanoparticles and resulted in strong localization of electromagnetic fields leading to intense signals in surface-enhanced Raman spectroscopy. The scalability and simplicity of ESPNL hold great promise in patterning of a broad range of polymer thin films for different applications. © 2017 American Chemical Society.

  • Asymmetric Supercapacitors Based on Reduced Graphene Oxide with Different Polyoxometalates as Positive and Negative Electrodes

    Dubal D.P., Chodankar N.R., Vinu A., Kim D.-H., Gomez-Romero P. ChemSusChem; 10 (13): 2742 - 2750. 2017. 10.1002/cssc.201700792.

    Novel Energy-Oriented Materials

    Nanofabrication using a “bottom-up” approach of hybrid electrode materials into a well-defined architecture is essential for next-generation miniaturized energy storage devices. This paper describes the design and fabrication of reduced graphene oxide (rGO)/polyoxometalate (POM)-based hybrid electrode materials and their successful exploitation for asymmetric supercapacitors. First, redox active nanoclusters of POMs [phosphomolybdic acid (PMo12) and phosphotungstic acid (PW12)] were uniformly decorated on the surface of rGO nanosheets to take full advantage of both charge-storing mechanisms (faradaic from POMs and electric double layer from rGO). The as-synthesized rGO-PMo12 and rGO-PW12 hybrid electrodes exhibited impressive electrochemical performances with specific capacitances of 299 (269 mF cm−2) and 370 F g−1 (369 mF cm−2) in 1 m H2SO4 as electrolyte at 5 mA cm−2. An asymmetric supercapacitor was then fabricated using rGO-PMo12 as the positive and rGO-PW12 as the negative electrode. This rGO-PMo12∥rGO-PW12 asymmetric cell could be successfully cycled in a wide voltage window up to 1.6 V and hence exhibited an excellent energy density of 39 Wh kg−1 (1.3 mWh cm−3) at a power density of 658 W kg−1 (23 mW cm−3). © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

  • Bioluminescent nanopaper for rapid screening of toxic substances

    Liu J., Morales-Narváez E., Orozco J., Vicent T., Zhong G., Merkoçi A. Nano Research; : 1 - 12. 2017. 10.1007/s12274-017-1610-7.

    Nanobioelectronics and Biosensors

    Environmental pollution is threatening human health and ecosystems as a result of modern agricultural techniques and industrial progress. A simple nanopaper-based platform coupled with luminescent bacteria Aliivibrio fischeri (A. fischeri) as a bio-indicator is presented here, for rapid and sensitive evaluation of contaminant toxicity. When exposed to toxicants, the luminescence inhibition of A. fischeri-decorated bioluminescent nanopaper (BLN) can be quantified and analyzed to classify the toxicity level of a pollutant. The BLN composite was characterized in terms of morphology and functionality. Given the outstanding biocompatibility of nanocellulose for bacterial proliferation, BLN achieved high sensitivity with a low cost and simplified procedure compared to conventional instruments for laboratory use only. The broad applicability of BLN devices to environmental samples was studied in spiked real matrices (lake and sea water), and their potential for direct and in situ toxicity screening was demonstrated. The BLN architecture not only survives but also maintains its function during freezing and recycling processes, endowing the BLN system with competitive advantages as a deliverable, ready-to-use device for large-scale manufacturing. The novel luminescent bacteria-immobilized, nanocelullose-based device shows outstanding abilities for toxicity bioassays of hazardous compounds, bringing new possibilities for cheap and efficient environmental monitoring of potential contamination. [Figure not available: see fulltext.] © 2017 Tsinghua University Press and Springer-Verlag GmbH Germany

  • Biosensors for plant pathogen detection

    Khater M., de la Escosura-Muñiz A., Merkoçi A. Biosensors and Bioelectronics; 93: 72 - 86. 2017. 10.1016/j.bios.2016.09.091.

    Nanobioelectronics and Biosensors

    Infectious plant diseases are caused by pathogenic microorganisms such as fungi, bacteria, viruses, viroids, phytoplasma and nematodes. Worldwide, plant pathogen infections are among main factors limiting crop productivity and increasing economic losses. Plant pathogen detection is important as first step to manage a plant disease in greenhouses, field conditions and at the country boarders. Current immunological techniques used to detect pathogens in plant include enzyme-linked immunosorbent assays (ELISA) and direct tissue blot immunoassays (DTBIA). DNA-based techniques such as polymerase chain reaction (PCR), real time PCR (RT-PCR) and dot blot hybridization have also been proposed for pathogen identification and detection. However these methodologies are time-consuming and require complex instruments, being not suitable for in-situ analysis. Consequently, there is strong interest for developing new biosensing systems for early detection of plant diseases with high sensitivity and specificity at the point-of-care. In this context, we revise here the recent advancement in the development of advantageous biosensing systems for plant pathogen detection based on both antibody and DNA receptors. The use of different nanomaterials such as nanochannels and metallic nanoparticles for the development of innovative and sensitive biosensing systems for the detection of pathogens (i.e. bacteria and viruses) at the point-of-care is also shown. Plastic and paper-based platforms have been used for this purpose, offering cheap and easy-to-use really integrated sensing systems for rapid on-site detection. Beside devices developed at research and development level a brief revision of commercially available kits is also included in this review. © 2016 Elsevier B.V.

  • Capacitive vs Faradaic Energy Storage in a Hybrid Cell with LiFePO4/RGO Positive Electrode and Nanocarbon Negative Electrode

    Cabán-Huertas Z., Dubal D.P., Ayyad O., Gómez-Romero P. Journal of the Electrochemical Society; 164 (1): A6140 - A6146. 2017. 10.1149/2.0211701jes.

    Novel Energy-Oriented Materials

    We report an advanced device based on a Nitrogen-doped Carbon Nanopipes (N-CNP) negative electrode and a lithium iron phosphate (LiFePO4) positive electrode. We carefully balanced the cell composition (charge balance) and suppressed the initial irreversible capacity of the anode in the round of few cycles.We demonstrated an optimal performance in terms of specific capacity 170 mAh/g of LiFePO4 with energy density of about 203 Wh kg-1 and a stable operation for over 100 charge-discharge cycles. The components of this device (combining capacitive and faradaic electrodes) are low cost and easily scalable. This device has a performance comparable to those offered by the present technology of LIBs with the potential for faster charging; hence, we believe that the results disclosed in this work may open up new opportunities for energy storage devices. © The Author(s) 2016. Published by ECS.

  • Carborane bis-pyridylalcohols as linkers for coordination polymers: Synthesis, crystal structures, and guest-framework dependent mechanical properties

    Tsang M.Y., Rodríguez-Hermida S., Stylianou K.C., Tan F., Negi D., Teixidor F., Viñas C., Choquesillo-Lazarte D., Verdugo-Escamilla C., Guerrero M., Sort J., Juanhuix J., Maspoch D., Planas J.G. Crystal Growth and Design; 17 (2): 846 - 857. 2017. 10.1021/acs.cgd.6b01682.

    Supramolecular NanoChemistry and Materials

    We report the synthesis and characterization of six novel coordination polymers (CPs) based on M(II) (M: Zn and Co), di-, tri-, and tetracarboxylate linkers and two novel bis-pyridylalcohol 1,7-bis{(pyridin-n′-yl)methanol}-1,7-dicarba-closo-dodecaboranes (n′ = 3, L1; n′ = 4, L2) ligands. The polycarboxylates are terephthalic acid (H2BDC), 1,3,5-benzenetricarboxylic acid (H3BTB), and 1,2,4,5-Tetrakis(4-carboxyphenyl)benzene (H4TCPB). Structural description of CPs reveals the flexibility of the carborane ligands and their ability to construct extended structures. The CP containing Co(II), BTB, and L2 behaves as a crystalline sponge for a variety of guests, showing a higher affinity for aromatic guest molecules. Single-crystal nanoindentation experiments indicate that a high number of specific interactions between the guests and the CP framework result in a high elastic modulus and hardness values. © 2016 American Chemical Society.

  • Cationic liposomal vectors incorporating a bolaamphiphile for oligonucleotide antimicrobials

    Mamusa M., Sitia L., Barbero F., Ruyra A., Calvo T.D., Montis C., Gonzalez-Paredes A., Wheeler G.N., Morris C.J., McArthur M., Berti D. Biochimica et Biophysica Acta - Biomembranes; 1859 (10): 1767 - 1777. 2017. 10.1016/j.bbamem.2017.06.006.

    Inorganic Nanoparticles

    Antibacterial resistance has become a serious crisis for world health over the last few decades, so that new therapeutic approaches are strongly needed to face the threat of resistant infections. Transcription factor decoys (TFD) are a promising new class of antimicrobial oligonucleotides with proven in vivo activity when combined with a bolaamphiphilic cationic molecule, 12-bis-THA. These two molecular species form stable nanoplexes which, however, present very scarce colloidal stability in physiological media, which poses the challenge of drug formulation and delivery. In this work, we reformulated the 12-bis-THA/TFD nanoplexes in a liposomal carrier, which retains the ability to protect the oligonucleotide therapeutic from degradation and deliver it across the bacterial cell wall. We performed a physical-chemical study to investigate how the incorporation of 12-bis-THA and TFD affects the structure of POPC- and POPC/DOPE liposomes. Analysis was performed using dynamic light scattering (DLS), ζ-potential measurements, small-angle x-ray scattering (SAXS), and steady-state fluorescence spectroscopy to better understand the structure of the liposomal formulations containing the 12-bis-THA/TFD complexes. Oligonucleotide delivery to model Escherichia coli bacteria was assessed by means of confocal scanning laser microscopy (CLSM), evidencing the requirement of a fusogenic helper lipid for transfection. Preliminary biological assessments suggested the necessity of further development by modulation of 12-bis-THA concentration in order to optimize its therapeutic index, i.e. the ratio of antibacterial activity to the observed cytotoxicity. In summary, POPC/DOPE/12-bis-THA liposomes appear as promising formulations for TFD delivery. © 2017 Elsevier B.V.

  • Characterization of industrial Coolant Fluids and continuous ageing monitoring by wireless node—Enabled fiber optic sensors

    El Sachat A., Meristoudi A., Markos C., Sakellariou A., Papadopoulos A., Katsikas S., Riziotis C. Sensors (Switzerland); 17 (3, 568) 2017. 10.3390/s17030568.

    Phononic and Photonic Nanostructures

    Environmentally robust chemical sensors for monitoring industrial processes or infrastructures are lately becoming important devices in industry. Low complexity and wireless enabled characteristics can offer the required flexibility for sensor deployment in adaptable sensing networks for continuous monitoring and management of industrial assets. Here are presented the design, development and operation of a class of low cost photonic sensors for monitoring the ageing process and the operational characteristics of coolant fluids used in an industrial heavy machinery infrastructure. The chemical, physical and spectroscopic characteristics of specific industrial-grade coolant fluids were analyzed along their entire life cycle range, and proper parameters for their efficient monitoring were identified. Based on multimode polymer or silica optical fibers, wide range (3–11) pH sensors were developed by employing sol-gel derived pH sensitive coatings. The performances of the developed sensors were characterized and compared, towards their coolants’ ageing monitoring capability, proving their efficiency in such a demanding application scenario and harsh industrial environment. The operating characteristics of this type of sensors allowed their integration in an autonomous wireless sensing node, thus enabling the future use of the demonstrated platform in wireless sensor networks for a variety of industrial and environmental monitoring applications. © 2017 by the authors. Licensee MDPI, Basel, Switzerland.

  • Charge Transfer Characterization of ALD-Grown TiO2 Protective Layers in Silicon Photocathodes

    Ros C., Andreu T., Hernández-Alonso M.D., Penelas-Pérez G., Arbiol J., Morante J.R. ACS Applied Materials and Interfaces; 9 (21): 17932 - 17941. 2017. 10.1021/acsami.7b02996.

    Advanced Electron Nanoscopy

    A critical parameter for the implementation of standard high-efficiency photovoltaic absorber materials for photoelectrochemical water splitting is its proper protection from chemical corrosion while remaining transparent and highly conductive. Atomic layer deposited (ALD) TiO2 layers fulfill material requirements while conformally protecting the underlying photoabsorber. Nanoscale conductivity of ALD TiO2 protective layers on silicon-based photocathodes has been analyzed, proving that the conduction path is through the columnar crystalline structure of TiO2. Deposition temperature has been explored from 100 to 300 °C, and a temperature threshold is found to be mandatory for an efficient charge transfer, as a consequence of layer crystallization between 100 and 200 °C. Completely crystallized TiO2 is demonstrated to be mandatory for long-term stability, as seen in the 300 h continuous operation test. © 2017 American Chemical Society.

  • Composite Salt in Porous Metal-Organic Frameworks for Adsorption Heat Transformation

    Garzón-Tovar L., Pérez-Carvajal J., Imaz I., Maspoch D. Advanced Functional Materials; 27 (21, 1606424) 2017. 10.1002/adfm.201606424.

    Supramolecular NanoChemistry and Materials

    Adsorptive heat transformation systems such as adsorption thermal batteries and chillers can provide space heating and cooling in a more environmental friendly way. However, their use is still hindered by their relatively poor performances and large sizes due to the limited properties of solid adsorbents. Here, the spray-drying continuous-flow synthesis of a new type of solid adsorbents that results from combining metal-organic frameworks (MOFs), such as UiO-66, and hygroscopic salts, such as CaCl2 has been reported. These adsorbents, commonly named as composite salt in porous matrix (CSPM) materials, allow improving the water uptake capabilities of MOFs while preventing their dissolution in the water adsorbed; a common characteristic of these salts due to the deliquescence effect. It is anticipated that MOF-based CSPMs, in which the percentage of salt can be tuned, are promising candidates for thermal batteries and chillers. In these applications, it is showed that a CSPM made of UiO-66 and CaCl2 (38% w/w) exhibits a heat storage capacity of 367 kJ kg−1, whereas a second CSPM made of UiO-66 and CaCl2 (53% w/w) shows a specific cooling power of 631 W kg−1 and a coefficient of performance of 0.83, comparable to the best solid adsorbents reported so far. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

  • Computer-assisted cognitive remediation therapy in schizophrenia: Durability of the effects and cost-utility analysis

    Garrido G., Penadés R., Barrios M., Aragay N., Ramos I., Vallès V., Faixa C., Vendrell J.M. Psychiatry Research; 254: 198 - 204. 2017. 10.1016/j.psychres.2017.04.065.

    The durability of computer–assisted cognitive remediation (CACR) therapy over time and the cost-effectiveness of treatment remains unclear. The aim of the current study is to investigate the effectiveness of CACR and to examine the use and cost of acute psychiatric admissions before and after of CACR. Sixty-seven participants were initially recruited. For the follow-up study a total of 33 participants were enrolled, 20 to the CACR condition group and 13 to the active control condition group. All participants were assessed at baseline, post-therapy and 12 months post-therapy on neuropsychology, QoL and self-esteem measurements. The use and cost of acute psychiatric admissions were collected retrospectively at four assessment points: baseline, 12 months post-therapy, 24 months post-therapy, and 36 months post-therapy. The results indicated that treatment effectiveness persisted in the CACR group one year post-therapy on neuropsychological and well-being outcomes. The CACR group showed a clear decrease in the use of acute psychiatric admissions at 12, 24 and 36 months post-therapy, which lowered the global costs the acute psychiatric admissions at 12, 24 and 36 months post-therapy. The CACR is durable over at least a 12-month period, and CACR may be helping to reduce health care costs for schizophrenia patients. © 2017 Elsevier Ireland Ltd

  • Confining Functional Nanoparticles into Colloidal Imine-Based COF Spheres by a Sequential Encapsulation–Crystallization Method

    Rodríguez-San-Miguel D., Yazdi A., Guillerm V., Pérez-Carvajal J., Puntes V., Maspoch D., Zamora F. Chemistry - A European Journal; 23 (36): 8623 - 8627. 2017. 10.1002/chem.201702072.

    Supramolecular NanoChemistry and Materials | Inorganic Nanoparticles

    Here, a two-step method is reported that enables imparting new functionalities to covalent organic frameworks (COFs) by nanoparticle confinement. The direct reaction between 1,3,5-tris(4-aminophenyl)benzene and 1,3,5-benzenetricarbaldehyde in the presence of a variety of metallic/metal-oxide nanoparticles resulted in embedding of the nanoparticles in amorphous and non-porous imine-linked polymer organic spheres (NP@a-1). Post-treatment reactions of NP@a-1 with acetic acid under reflux led to crystalline and porous imine-based COF-hybrid spheres (NP@c-1). Interestingly, Au@c-1 and Pd@c-1 were found to be catalytically active. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

  • Conserved effects and altered trafficking of Cetuximab antibodies conjugated to gold nanoparticles with precise control of their number and orientation

    García-Fernández L., Garcia-Pardo J., Tort O., Prior I., Brust M., Casals E., Lorenzo J., Puntes V.F. Nanoscale; 9 (18): 6111 - 6121. 2017. 10.1039/c7nr00947j.

    Inorganic Nanoparticles

    Gold nanoparticles (17 nm) have been functionalized with the antiangiogenic monoclonal antibody drug Cetuximab at a well-defined orientation and coverage density of antibodies. Functionalization has been carried out through site-directed chemistry via the selective oxidation of the carbohydrate moiety of antibodies linked to a thiolated hydrazide. A431 tumor cells have been exposed to these conjugates for in vitro evaluation of their effects. In addition to epithelial growth factor receptor blocking, trafficking and signaling alterations were also observed. Thus, the blocking effects of Cetuximab were increased and sustained for a longer time when associated with the nanoparticles. Enhancing antibody therapy effects by decreasing the needed dose and prolonging its effect by avoiding receptor recycling may serve to obtain increased therapeutic benefits for immunotherapy. © The Royal Society of Chemistry 2017.

  • Continuous One-Step Synthesis of Porous M-XF6-Based Metal-Organic and Hydrogen-Bonded Frameworks

    Guillerm V., Garzón-Tovar L., Yazdi A., Imaz I., Juanhuix J., Maspoch D. Chemistry - A European Journal; 23 (28): 6829 - 6835. 2017. 10.1002/chem.201605507.

    Supramolecular NanoChemistry and Materials

    Metal-organic frameworks (MOFs) built up from connecting M-XF6 pillars through N-donor ligands are among the most attractive adsorbents and separating agents for CO2 and hydrocarbons today. The continuous, one-step spray-drying synthesis of several members of this isoreticular MOF family varying the anionic pillar (XF6=[SiF6]2− and [TiF6]2−), the N-donor organic ligand (pyrazine and 4,4′-bipyridine) and the metal ion (M=Co, Cu and Zn) is demonstrated here. This synthetic method allows them to be obtained in the form of spherical superstructures assembled from nanosized crystals. As confirmed by CO2 and N2 sorption studies, most of the M-XF6-based MOFs synthesised through spray-drying can be considered “ready-to-use” sorbents as they do not need additional purification and time consuming solvent exchange steps to show comparable porosity and sorption properties with the bulk/single-crystal analogues. Stability tests of nanosized M-SiF6-based MOFs confirm their low stability in most solvents, including water and DMF, highlighting the importance of protecting them once synthesised. Finally, for the first time it was shown that the spray-drying method can also be used to assemble hydrogen-bonded open networks, as evidenced by the synthesis of MPM-1-TIFSIX. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

  • Core-shell Au/CeO2 nanoparticles supported in UiO-66 beads exhibiting full CO conversion at 100 °c

    Yazdi A., Abo Markeb A., Garzón-Tovar L., Patarroyo J., Moral-Vico J., Alonso A., Sánchez A., Bastus N., Imaz I., Font X., Puntes V., Maspoch D. Journal of Materials Chemistry A; 5 (27): 13966 - 13970. 2017. 10.1039/c7ta03006a.

    Supramolecular NanoChemistry and Materials | Inorganic Nanoparticles

    Hybrid core-shell Au/CeO2 nanoparticles (NPs) dispersed in UiO-66 shaped into microspherical beads are created using the spray-drying continuous-flow method. The combined catalytic properties of nanocrystalline CeO2 and Au in a single particle and the support and protective function of porous UiO-66 beads make the resulting composites show good performances as catalysts for CO oxidation (T50 = 72 °C; T100 = 100 °C) and recyclability. © 2017 The Royal Society of Chemistry.

  • Cryogenic characterisation and modelling of commercial SiC MOSFETs

    Woodend L.J., Gammon P.M., Shah V.A., Pérez-Tomás A., Li F., Hamilton D.P., Myronov M., Mawby P.A. Materials Science Forum; 897 MSF: 557 - 560. 2017. 10.4028/www.scientific.net/MSF.897.557.

    Oxide Nanophysics

    Two commercial 1.2 kV SiC MOSFETs have been extensively characterised from 30 to 320 K. The temperature dependence of their I/V characteristics, threshold voltage, and breakdown voltage has been examined and are presented in this paper. Overall, the measured characteristics of both devices demonstrate very similar temperature dependencies and it is shown that below ~100 K any further decrease in temperature has little effect on any of the tested characteristics. Increasing temperature beyond 100 K results in a decrease in drain current for a given drain-source and gatesource voltage, a decrease in threshold voltage, and an increase in breakdown voltage. Successful attempts have been made to model the results of these tests by applying theories found in the literature. © 2017 Trans Tech Publications, Switzerland.

  • Cryptophane-cladded interferometric waveguide sensor for aqueous methane detection

    Jágerská J., Dullo F.T., Lindecrantz S.M., Börgers J.M., Hansen J.H., Lechuga L.M., Hellesø O.G. Optics InfoBase Conference Papers; Part F43-CLEO_AT 2017 2017. 10.1364/CLEO_AT.2017.AM3B.4.

    NanoBiosensors and Bioanalytical Applications

    A nanophotonic sensor for sensitive detection of methane in water solution is presented. Cryptophane-A doped waveguide cladding provides for methane pre-concentration on a chip, resulting in a detection limit of 60 ppm (86 nM). © 2017 OSA.

  • Design of Hierarchical Surfaces for Tuning Wetting Characteristics

    Fernández A., Francone A., Thamdrup L.H., Johansson A., Bilenberg B., Nielsen T., Guttmann M., Sotomayor Torres C.M., Kehagias N. ACS Applied Materials and Interfaces; 9 (8): 7701 - 7709. 2017. 10.1021/acsami.6b13615.

    Phononic and Photonic Nanostructures

    Patterned surfaces with tunable wetting properties are described. A hybrid hierarchical surface realized by combining two different materials exhibits different wetting states, depending on the speed of impingement of the water droplets. Both "lotus" (high contact angle and low adhesion) and "petal" (high contact angle and high adhesion) states were observed on the same surface without the need of any modification of the surface. The great difference between the capillary pressures exerted by the microstructures and nanostructures was the key factor that allowed us to tailor effectively the adhesiveness of the water droplets. Having a low capillary pressure for the microstructures and a high capillary pressure for the nanostructures, we allow to the surface the possibility of being in a lotus state or in a petal state. © 2017 American Chemical Society.

  • Direct and label-free detection of the human growth hormone in urine by an ultrasensitive bimodal waveguide biosensor

    González-Guerrero A.B., Maldonado J., Dante S., Grajales D., Lechuga L.M. Journal of Biophotonics; 10 (1): 61 - 67. 2017. 10.1002/jbio.201600154.

    NanoBiosensors and Bioanalytical Applications

    A label-free interferometric transducer showing a theoretical detection limit for homogeneous sensing of 5 × 10–8 RIU, being equivalent to a protein mass coverage resolution of 2.8 fg mm–2, is used to develop a high sensitive biosensor for protein detection. The extreme sensitivity of this transducer combined with a selective bioreceptor layer enables the direct evaluation of the human growth hormone (hGH) in undiluted urine matrix in the 10 pg mL–1 range. (Figure presented.). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

  • Direct electrodeposition of imidazole modified poly(pyrrole) copolymers: synthesis, characterization and supercapacitive properties

    Wolfart F., Hryniewicz B.M., Marchesi L.F., Orth E.S., Dubal D.P., Gómez-Romero P., Vidotti M. Electrochimica Acta; 243: 260 - 269. 2017. 10.1016/j.electacta.2017.05.082.

    Novel Energy-Oriented Materials

    In this manuscript we report the direct electrosynthesis of a new conducting copolymer based on the incorporation of imidazole molecules within the polypyrrole chain. Different proportions of the monomers were tested during the direct electropolymerization of the copolymer. The resulting materials were characterized by electrochemical and spectroscopic techniques (Raman and XPS) and a mechanism of polymerization is proposed. Our findings showed that imidazole acts as an inhibitor of the polymerization process, decreasing the overall number of actives sites for the polymerization on the electrode surface producing a polymeric morphology very different compared with pure polypyrrole, as observed by Scanning Electron Microscopy images and corroborated by Electrochemical Impedance Spectroscopy. This behavior significantly affects the supercapacitive performance of the resulting p(Py-IMZ) modified electrodes where the specific capacitance of the material increased from 122 to 201 Fg−1 (64%) at 10 mV s−1. Furthermore, a unique pseudo-capacitive behavior described herein emphasizes the role of the imidazole as inductor of the morphology and co-monomer in the unique electrochemical signature of the material. The results suggest that the incorporation of IMZ increases the specific capacitance of PPy electrode by around 64%. © 2017 Elsevier Ltd

  • Directional elastic wave propagation in high-aspect-ratio photoresist gratings: Liquid infiltration and aging

    Alonso-Redondo E., Gueddida A., Li J., Graczykowski B., Sotomayor Torres C.M., Pennec Y., Yang S., Djafari-Rouhani B., Fytas G. Nanoscale; 9 (8): 2739 - 2747. 2017. 10.1039/c6nr08312a.

    Phononic and Photonic Nanostructures

    Determination of the mechanical properties of nanostructured soft materials and their composites in a quantitative manner is of great importance to improve the fidelity in their fabrication and to enable the subsequent reliable utility. Here, we report on the characterization of the elastic and photoelastic parameters of a periodic array of nanowalls (grating) by the non-invasive Brillouin light scattering technique and finite element calculations. The resolved elastic vibrational modes in high and low aspect ratio nanowalls reveal quantitative and qualitative differences related to the two-beam interference lithography fabrication and subsequent aging under ambient conditions. The phononic properties, namely the dispersion relations, can be drastically altered by changing the surrounding material of the nanowalls. Here we demonstrate that liquid infiltration turns the phononic function from a single-direction phonon-guiding to an anisotropic propagation along the two orthogonal directions. The susceptibility of the phononic behavior to the infiltrating liquid can be of unusual benefits, such as sensing and alteration of the materials under confinement. © The Royal Society of Chemistry 2017.

  • Domain wall magnetoresistance in BiFeO3 thin films measured by scanning probe microscopy

    Domingo N., Farokhipoor S., Santiso J., Noheda B., Catalan G. Journal of Physics Condensed Matter; 29 (33, 334003) 2017. 10.1088/1361-648X/aa7a24.

    Oxide Nanophysics | Nanomaterials Growth Division

    We measure the magnetotransport properties of individual 71° domain walls in multiferroic BiFeO3 by means of conductive-atomic force microscopy (C-AFM) in the presence of magnetic fields up to one Tesla. The results suggest anisotropic magnetoresistance at room temperature, with the sign of the magnetoresistance depending on the relative orientation between the magnetic field and the domain wall plane. A consequence of this finding is that macroscopically averaged magnetoresistance measurements for domain wall bunches are likely to underestimate the magnetoresistance of each individual domain wall. © 2017 IOP Publishing Ltd.

  • Editorial

    Dubal D., Holze R. Journal of Solid State Electrochemistry; 21 (9): 2463 - 2465. 2017. 10.1007/s10008-016-3469-z.

    [No abstract available]

  • Effect of the annealing on the power factor of un-doped cold-pressed SnSe

    Morales Ferreiro J.O., Diaz-Droguett D.E., Celentano D., Reparaz J.S., Sotomayor Torres C.M., Ganguli S., Luo T. Applied Thermal Engineering; 111: 1426 - 1432. 2017. 10.1016/j.applthermaleng.2016.07.198.

    Phononic and Photonic Nanostructures

    Tin Selenide (SnSe), a thermoelectric material of the chalcogenide family, has attracted tremendous interest in the past few years due to its unprecedented thermoelectric figure-of-merit, ZT, of 2.6. In this work we have carried out an experimental study of the impact of annealing on the thermoelectric properties of polycrystalline SnSe formed by cold-pressing un-doped SnSe powders with a Hall carrier concentration of 5.37 × 1017 cm−3. The crystalline structure and morphology of the samples are characterized and properties, including electrical conductivity, Seebeck coefficient and thermal conductivity, are measured. It is found that thermal annealing has a large impact on both the microstructure and the thermoelectric properties. Notably, annealing leads to re-alignment of crystalline domains, increase in Seebeck coefficient by a factor of as much as 3, and increase in the electrical conductivity. A peak ZT of 0.11 was achieved at 772 K which is smaller than un-doped polycrystalline SnSe. © 2016 Elsevier Ltd

  • Electric-Field-Adjustable Time-Dependent Magnetoelectric Response in Martensitic FeRh Alloy

    Fina I., Quintana A., Padilla-Pantoja J., Martí X., Macià F., Sánchez F., Foerster M., Aballe L., Fontcuberta J., Sort J. ACS Applied Materials and Interfaces; 9 (18): 15577 - 15582. 2017. 10.1021/acsami.7b00476.

    Steady or dynamic magnetoelectric response, selectable and adjustable by only varying the amplitude of the applied electric field, is found in a multiferroic FeRh/PMN-PT device. In-operando time-dependent structural, ferroelectric, and magnetoelectric characterizations provide evidence that, as in magnetic shape memory martensitic alloys, the observed distinctive magnetoelectric responses are related to the time-dependent relative abundance of antiferromagnetic-ferromagnetic phases in FeRh, unbalanced by voltage-controlled strain. This flexible magnetoelectric response can be exploited not only for energy-efficient memory operations but also in other applications, where multilevel and/or transient responses are required. © 2017 American Chemical Society.

  • Electrical and Thermal Transport in Coplanar Polycrystalline Graphene-hBN Heterostructures

    Barrios-Vargas J.E., Mortazavi B., Cummings A.W., Martinez-Gordillo R., Pruneda M., Colombo L., Rabczuk T., Roche S. Nano Letters; 17 (3): 1660 - 1664. 2017. 10.1021/acs.nanolett.6b04936.

    Theoretical and Computational Nanoscience

    We present a theoretical study of electronic and thermal transport in polycrystalline heterostructures combining graphene (G) and hexagonal boron nitride (hBN) grains of varying size and distribution. By increasing the hBN grain density from a few percent to 100%, the system evolves from a good conductor to an insulator, with the mobility dropping by orders of magnitude and the sheet resistance reaching the MΩ regime. The Seebeck coefficient is suppressed above 40% mixing, while the thermal conductivity of polycrystalline hBN is found to be on the order of 30-120 Wm-1 K-1. These results, agreeing with available experimental data, provide guidelines for tuning G-hBN properties in the context of two-dimensional materials engineering. In particular, while we proved that both electrical and thermal properties are largely affected by morphological features (e.g., by the grain size and composition), we find in all cases that nanometer-sized polycrystalline G-hBN heterostructures are not good thermoelectric materials. © 2017 American Chemical Society.

  • Electrochemical behavior of nanostructured La0.8Sr0.2MnO3 as cathodes for solid oxide fuel cells

    Sacanell J., Sánchez J.H., Rubio Lopez A.E., Martinelli H., Siepe J., Leyva A.G., Ferrari V.P., Pruneda M., Juan D., Lamas D.G. ECS Transactions; 78 (1): 667 - 675. 2017. 10.1149/07801.0667ecst.

    La0.8Sr0.2MnO3 (LSM) is one of the most commonly used cathodes in Solid Oxide Fuel Cells (SOFC). In spite of the fact that nanostructured cathodes are expected to display improved performance, the high operating temperature (∼ 1000°C) of LSM-based SOFCs hinders their stability. In the present work, we have developed nanostructured cathodes prepared from LSM nanotubes of enhanced performance, allowing its use at lower temperatures (∼ 800°C). We observed that our cathodes have qualitative improvements compared with microstructured materials: firstly, the diffusion in the gas phase is optimized to a negligible level and secondly, evidence of ionic conduction is found, which is extremely rare in LSM cathodes. We propose that this important change in the electrochemical properties is due to the nanostructuration of the cathode and deserves further attention, including the exploration of other materials. © The Electrochemical Society.

  • Electrochemical characterization of GaN surface states

    Winnerl A., Garrido J.A., Stutzmann M. Journal of Applied Physics; 122 (4, 045302) 2017. 10.1063/1.4995429.

    Advanced Electronic Materials and Devices

    In this work, we present a systematic study of the electrochemical properties of metal-organic chemical vapor deposition and hybrid vapor phase epitaxy grown n-type GaN in aqueous electrolytes. For this purpose, we perform cyclic voltammetry and impedance spectroscopy measurements over a wide range of potentials and frequencies, using a pure aqueous electrolyte and adding two different types of redox couples, as well as applying different surface treatments to the GaN electrodes. For Ga-polar GaN electrodes, the charge transfer to an electrolyte is dominated by surface states, which are not related to dislocations and are independent of the specific growth technique. These surface states can be modified by the surface treatment; they are generated by etching in HCl and are passivated by oxidation. Different surface defect states are present on N-polar GaN electrodes which do not significantly contribute to the charge transfer across the GaN/electrolyte interface. © 2017 Author(s).

  • Electrochemical synthesis: Monoclinic Cu2Se nano-dendrites with high performance for supercapacitors

    Shinde S.K., Ghodake G.S., Dubal D.P., Patel R.V., Saratale R.G., Kim D.-Y., Maile N.C., Koli R.R., Dhaygude H.D., Fulari V.J. Journal of the Taiwan Institute of Chemical Engineers; 75: 271 - 279. 2017. 10.1016/j.jtice.2017.01.028.

    Morphology is a key factor in designing novel nanomaterials with controlled functional properties for the electrochemical application. Herein, we demonstrate the supercapacitor applications of the copper selenide (Cu2Se) electrodes with different morphologies prepared by electrodeposition at -0.65, -0.75, and -0.85 V/SCE deposition potentials. The well-defined morphologies of the Cu2Se nanostructures have been useful to develop potential applications in the supercapacitor devices. The nanodendrite-like morphology obtained at the deposition potential -0.75 V/SCE showed maximum specific capacitance (688 F/g at 5 mV/s) as compared to the other morphologies. © 2017 Taiwan Institute of Chemical Engineers

  • Electrochemically reduced graphene and iridium oxide nanoparticles for inhibition-based angiotensin-converting enzyme inhibitor detection

    Kurbanoglu S., Rivas L., Ozkan S.A., Merkoçi A. Biosensors and Bioelectronics; 88: 122 - 129. 2017. 10.1016/j.bios.2016.07.109.

    Nanobioelectronics and Biosensors

    In this work, a novel biosensor based on electrochemically reduced graphene oxide and iridium oxide nanoparticles for the detection of angiotensin-converting enzyme inhibitor drug, captopril, is presented. For the preparation of the biosensor, tyrosinase is immobilized onto screen printed electrode by using 1-Ethyl-3-(3-dimethylaminopropyl)-carbodiimide and N-Hydroxysuccinimide coupling reagents, in electrochemically reduced graphene oxide and iridium oxide nanoparticles matrix. Biosensor response is characterized towards catechol, in terms of graphene oxide concentration, number of cycles to reduce graphene oxide, volume of iridium oxide nanoparticles and tyrosinase solution. The designed biosensor is used to inhibit tyrosinase activity by Captopril, which is generally used to treat congestive heart failure. It is an angiotensin-converting enzyme inhibitor that operates via chelating copper at the active site of tyrosinase and thioquinone formation. The captopril detections using both inhibition ways are very sensitive with low limits of detection: 0.019 µM and 0.008 µM for chelating copper at the active site of tyrosinase and thioquinone formation, respectively. The proposed methods have been successfully applied in captopril determination in spiked human serum and pharmaceutical dosage forms with acceptable recovery values. © 2016 Elsevier B.V.

  • Encapsulation of two-dimensional materials inside carbon nanotubes: Towards an enhanced synthesis of single-layered metal halides

    Sandoval S., Pach E., Ballesteros B., Tobias G. Carbon; 123: 129 - 134. 2017. 10.1016/j.carbon.2017.07.031.

    Force Probe Microscopy and Surface Nanoengineering | Electron Microscopy Division

    The unique properties of two-dimensional (2D) nanomaterials make them highly attractive for a wide range of applications. As a consequence, several top-down and bottom up approaches are being explored to isolate or synthesize single-layers of 2D materials in a reliable manner. Here we report on the synthesis of individual layers of several 2D van der Waals solids, namely CeI3, CeCl3, TbCl3 and ZnI2 by template-assisted growth using carbon nanotubes as directing agents, thus proving the versatility of this approach. Once confined, the metal halides can adopt different structures including single-layered metal halide nanotubes, which formation is greatly enhanced by increasing the temperature of synthesis. This opens up a new strategy for the isolation of individual layers of a wide variety of metal halides, a family of 2D materials that has been barely explored. © 2017 Elsevier Ltd

  • Enhanced Cooperativity in Supported Spin-Crossover Metal-Organic Frameworks

    Groizard T., Papior N., Le Guennic B., Robert V., Kepenekian M. Journal of Physical Chemistry Letters; 8 (14): 3415 - 3420. 2017. 10.1021/acs.jpclett.7b01248.

    The impact of surface deposition on cooperativity is explored in Au(111)-supported self-assembled metal-organic frameworks (MOFs) based on Fe(II) ions. Using a thermodynamic model, we first demonstrate that dimensionality reduction combined with deposition on a metal surface is likely to deeply enhance the spin-crossover cooperativity, going from γ3D = 16 K for the bulk material to γ2Dsupp = 386 K for its 2D supported derivative. On the basis of density functional theory, we then elucidate the electronic structure of a promising Fe-based MOF. A chemical strategy is proposed to turn a weakly interacting magnetic system into a strongly cooperative spin-crossover monolayer with γMOFAu(111) = 83 K. These results open a promising route to the fabrication of cooperative materials based on SCO Fe(II) platforms. © 2017 American Chemical Society.

  • Enhanced photoelectrochemical properties of nanoflower-like hexagonal CdSe0.6Te0.4: Effect of electron beam irradiation

    Shinde S.K., Ghodake G.S., Dubal D.P., Dhaygude H.D., Kim D.-Y., Fulari V.J. Journal of Industrial and Engineering Chemistry; 45: 92 - 98. 2017. 10.1016/j.jiec.2016.09.007.

    Novel Energy-Oriented Materials

    Present investigation deals with the effect of electron beam irradiation on the photoelectrochemical properties of cadmium selenium telluride (CdSe0.6Te0.4) thin films. Initially, CdSe0.6Te0.4 thin films were electrodeposited on fluorine doped tin oxide (FTO) coated glass and stainless steel substrates. Later, these CdSe0.6Te0.4 thin films were irradiated with high energy electron beam (10 MeV) of different doses from 10 to 30 kilograys (kGy). The effect of electron beam irradiation on different physico-chemical properties of CdSe0.6Te0.4 thin films such as morphological, structural, optical and photoelectrochemical has been investigated. It is observed that, the electron beam irradiation treatment considerably affects the properties of CdSe0.6Te0.4 thin films. The surface morphology of CdSe0.6Te0.4 thin films was changed from cauliflowers to nanoflowers, nanoroses and interconnected nanoflakes with doses of electron beams. Furthermore, the effect of electron beam irradiation on photoelectrochemical properties of CdSe0.6Te0.4 films was investigated. It is interesting to note that, the photoelectrochemical (PEC) properties of CdSe0.6Te0.4 thin films are extensively affected by electron beam irradiation. The photoconversion efficiency values of CdSe0.6Te0.4 films for different doses of electron beam are found to be 0.9%, 1.1%, 2.0% and 1.5%, respectively. © 2016

  • Epitaxial Growth of SrTiO3 Films on Cube-Textured Cu-Clad Substrates by PLD at Low Temperature Under Reducing Atmosphere

    Padilla J.A., Xuriguera E., Rodríguez L., Vannozzi A., Segarra M., Celentano G., Varela M. Nanoscale Research Letters; 12 (1, 226) 2017. 10.1186/s11671-017-1997-9.

    The growth of epitaxial {001}<100> SrTiO3 (STO) on low-cost cube-textured Cu-based clad substrate at low temperature was carried out by means of pulsed laser deposition (PLD). STO film was deposited in one step under a reducing atmosphere (5% H2 and 95% Ar mixture) to prevent the oxidation of the metal surface. The optimization of PLD parameters leads to a sharpest biaxial texture at a temperature as low as 500 °C and a thickness of 500 nm with a (100) STO layer. The upper limit of highly textured STO thickness was also investigated. The maximum thickness which retains the best quality {001}<100> texture is 800 nm, since the texture is preserved not only through the layer but also on the surface. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) measurements showed that STO films are continuous, dense, and smooth with very low roughness (between 5 and 7 nm). This paper describes the development of STO layer by means of PLD in absence of oxygen throughout the process, suggesting an alternative and effective method for growing highly {001}<100> textured STO layer on low-cost metal substrates. © 2017, The Author(s).

  • Evaluation of the immunological profile of antibody-functionalized metal-filled single-walled carbon nanocapsules for targeted radiotherapy

    Perez Ruiz De Garibay A., Spinato C., Klippstein R., Bourgognon M., Martincic M., Pach E., Ballesteros B., Ménard-Moyon C., Al-Jamal K.T., Tobias G., Bianco A. Scientific Reports; 7 ( 42605) 2017. 10.1038/srep42605.

    Force Probe Microscopy and Surface Nanoengineering | Electron Microscopy Division

    This study investigates the immune responses induced by metal-filled single-walled carbon nanotubes (SWCNT) under in vitro, ex vivo and in vivo settings. Either empty amino-functionalized CNTs [SWCNT-NH 2 (1)] or samarium chloride-filled amino-functionalized CNTs with [SmCl 3 @SWCNT-mAb (3)] or without [SmCl 3 @SWCNT-NH 2 (2)] Cetuximab functionalization were tested. Conjugates were added to RAW 264.7 or PBMC cells in a range of 1 μg/ml to 100 μg/ml for 24 h. Cell viability and IL-6/TNFα production were determined by flow cytometry and ELISA. Additionally, the effect of SWCNTs on the number of T lymphocytes, B lymphocytes and monocytes within the PBMC subpopulations was evaluated by immunostaining and flow cytometry. The effect on monocyte number in living mice was assessed after tail vein injection (150 μg of each conjugate per mouse) at 1, 7 and 13 days post-injection. Overall, our study showed that all the conjugates had no significant effect on cell viability of RAW 264.7 but conjugates 1 and 3 led to a slight increase in IL-6/TNFα. All the conjugates resulted in significant reduction in monocyte/macrophage cell numbers within PBMCs in a dose-dependent manner. Interestingly, monocyte depletion was not observed in vivo, suggesting their suitability for future testing in the field of targeted radiotherapy in mice. © The Author(s) 2017.

  • Facile and low cost oxidative conversion of MoS2 in α-MoO3: Synthesis, characterization and application

    Bortoti A.A., Gavanski A.D.F., Velazquez Y.R., Galli A., de Castro E.G. Journal of Solid State Chemistry; 252: 111 - 118. 2017. 10.1016/j.jssc.2017.05.006.

    This study describes a facile low cost route to synthesize the α-MoO3 through a conversion of the precursor MoS2 in oxidant media. The structure and morphology of the α-MoO3 were studied by high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The results show that α-MoO3 was obtained with reduced size, high purity, strongly-preferred orientation and structural defects, which ensures versatility and multifunctionality to this sample. For the purpose of applications, α-MoO3 was successfully employed in inverted organic solar cells devices as a possible alternative to the PEDOT:PSS in the hole transportation layer. © 2017 Elsevier Inc.

  • Ferroelectrics as Smart Mechanical Materials

    Cordero-Edwards K., Domingo N., Abdollahi A., Sort J., Catalan G. Advanced Materials; 2017. 10.1002/adma.201702210.

    Oxide Nanophysics

    The mechanical properties of materials are insensitive to space inversion, even when they are crystallographically asymmetric. In practice, this means that turning a piezoelectric crystal upside down or switching the polarization of a ferroelectric should not change its mechanical response. Strain gradients, however, introduce an additional source of asymmetry that has mechanical consequences. Using nanoindentation and contact-resonance force microscopy, this study demonstrates that the mechanical response to indentation of a uniaxial ferroelectric (LiNbO3) does change when its polarity is switched, and use this mechanical asymmetry both to quantify its flexoelectricity and to mechanically read the sign of its ferroelectric domains. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  • Field Effect in Graphene-Based van der Waals Heterostructures: Stacking Sequence Matters

    Stradi D., Papior N.R., Hansen O., Brandbyge M. Nano Letters; 17 (4): 2660 - 2666. 2017. 10.1021/acs.nanolett.7b00473.

    Stacked van der Waals (vdW) heterostructures where semiconducting two-dimensional (2D) materials are contacted by overlaid graphene electrodes enable atomically thin, flexible electronics. We use first-principles quantum transport simulations of graphene-contacted MoS2 devices to show how the transistor effect critically depends on the stacking configuration relative to the gate electrode. We can trace this behavior to the stacking-dependent response of the contact region to the capacitive electric field induced by the gate. The contact resistance is a central parameter and our observation establishes an important design rule for ultrathin devices based on 2D atomic crystals. © 2017 American Chemical Society.

  • Filling Single-Walled Carbon Nanotubes with Lutetium Chloride: A Sustainable Production of Nanocapsules Free of Nonencapsulated Material

    Kierkowicz M., González-Domínguez J.M., Pach E., Sandoval S., Ballesteros B., Da Ros T., Tobias G. ACS Sustainable Chemistry and Engineering; 5 (3): 2501 - 2508. 2017. 10.1021/acssuschemeng.6b02850.

    Force Probe Microscopy and Surface Nanoengineering | Electron Microscopy Division

    Filled carbon nanotubes are of interest for a wide variety of applications ranging from sensors to magnetoelectronic devices and going through the development of smart contrast and therapeutic agents in the biomedical field. In general, regardless of the method employed, bulk filling of carbon nanotubes results in the presence of a large amount of external nonencapsulated material. Therefore, further processing is needed to achieve a sample in which the selected payload is present only in the inner cavities of the nanotubes. Here, we report on a straightforward approach that allows the removal of nonencapsulated compounds in a time efficient and environmentally friendly manner, using water as a "green" solvent, while minimizing the residual waste. The results presented herein pave the way toward the production of large amounts of high-quality closed-ended filled nanotubes, also referred to as carbon nanocapsules, readily utilizable in the foreseen applications. © 2017 American Chemical Society.

  • Frequency response of electrolyte-gated graphene electrodes and transistors

    Drieschner S., Guimerà A., Cortadella R.G., Viana D., Makrygiannis E., Blaschke B.M., Vieten J., Garrido J.A. Journal of Physics D: Applied Physics; 50 (9, 095304) 2017. 10.1088/1361-6463/aa5443.

    Advanced Electronic Materials and Devices

    The interface between graphene and aqueous electrolytes is of high importance for applications of graphene in the field of biosensors and bioelectronics. The graphene/electrolyte interface is governed by the low density of states of graphene that limits the capacitance near the Dirac point in graphene and the sheet resistance. While several reports have focused on studying the capacitance of graphene as a function of the gate voltage, the frequency response of graphene electrodes and electrolyte-gated transistors has not been discussed so far. Here, we report on the impedance characterization of single layer graphene electrodes and transistors, showing that due to the relatively high sheet resistance of graphene, the frequency response is governed by the distribution of resistive and capacitive circuit elements along the graphene/electrolyte interface. Based on an analytical solution for the impedance of the distributed circuit elements, we model the graphene/electrolyte interface both for the electrode and the transistor configurations. Using this model, we can extract the relevant material and device parameters such as the voltage-dependent intrinsic sheet and series resistances as well as the interfacial capacitance. The model also provides information about the frequency threshold of electrolyte-gated graphene transistors, above which the device exhibits a non-resistive response, offering an important insight into the suitable frequency range of operation of electrolyte-gated graphene devices. © 2017 IOP Publishing Ltd.

  • Functional dependence of resonant harmonics on nanomechanical parameters in dynamic mode atomic force microscopy

    Gramazio F., Lorenzoni M., Pérez-Murano F., Trinidad E.R., Staufer U., Fraxedas J. Beilstein Journal of Nanotechnology; 8 (1, 90) 2017. 10.3762/bjnano.8.90.

    Force Probe Microscopy and Surface Nanoengineering

    We present a combined theoretical and experimental study of the dependence of resonant higher harmonics of rectangular cantilevers of an atomic force microscope (AFM) as a function of relevant parameters such as the cantilever force constant, tip radius and free oscillation amplitude as well as the stiffness of the sample's surface. The simulations reveal a universal functional dependence of the amplitude of the 6th harmonic (in resonance with the 2nd flexural mode) on these parameters, which can be expressed in terms of a gun-shaped function. This analytical expression can be regarded as a practical tool for extracting qualitative information from AFM measurements and it can be extended to any resonant harmonics. The experiments confirm the predicted dependence in the explored 3-45 N/m force constant range and 2-345 GPa sample's stiffness range. For force constants around 25 N/m, the amplitude of the 6th harmonic exhibits the largest sensitivity for ultrasharp tips (tip radius below 10 nm) and polymers (Young's modulus below 20 GPa). © 2017 Gramazio et al.

  • Functional oxide as an extreme high-k dielectric towards 4H-SiC MOSFET incorporation

    Russell S.A.O., Jennings M.R., Dai T., Li F., Hamilton D.P., Fisher C.A., Sharma Y.K., Mawby P.A., Pérez-Tomás A. Materials Science Forum; 897 MSF: 155 - 158. 2017. 10.4028/www.scientific.net/MSF.897.155.

    Oxide Nanophysics

    MOS Capacitors are demonstrated on 4H-SiC using an octahedral ABO3 ferroic thin-film as a dielectric prepared on several buffer layers. Five samples were prepared: ABO3 on SiC, ABO3 on SiC with a SiO2 buffer (10 nm and 40 nm) and ABO3 on SiC with an Al2O3 buffer (10nm and 40 nm). Depending on the buffer material the oxide forms in either the pyrochlore or perovskite phase. A better lattice match with the Al2O3 buffer yields a perovskite phase with internal switchable dipoles. Hysteresis polarization-voltage loops show an oxide capacitance of ~ 0.2 μF/cm2 in the accumulation region indicating a dielectric constant of ~120. © 2017 Trans Tech Publications, Switzerland.

  • Functionalization of Polypyrrole Nanopipes with Redox-Active Polyoxometalates for High Energy Density Supercapacitors

    Dubal D.P., Ballesteros B., Mohite A.A., Gómez-Romero P. ChemSusChem; 10 (4): 731 - 737. 2017. 10.1002/cssc.201601610.

    Novel Energy-Oriented Materials | Electron Microscopy Division

    Hybrid materials are very attractive for the fabrication of high-performance supercapacitors. Here, we have explored organic–inorganic hybrid materials based on open-end porous 1 D polypyrrole nanopipes (PPy-NPipes) and heteropolyoxometalates (phosphotungstate ([PW12O40]3−, PW12) or phosphomolybdate ([PMo12O40]3−, PMo12)) that display excellent areal capacitances. Two different hybrid materials (PMo12@PPy and PW12@PPy) were effectively synthesized and used for symmetric supercapacitors. The anchoring of the inorganic nanoclusters onto the conducting polymer nanopipes led to electrodes that stood up to our best expectations exhibiting outstanding areal capacitances that are almost 1.5 to 2 fold higher than that of pristine PPy-NPipes. In addition, symmetric cells based on PMo12@PPy and PW12@PPy hybrid electrodes were fabricated and showed significant improvement in cell performance with very high volumetric capacitances in the range of 6.3–6.8 F cm−3(considering the volume of whole device). Indeed, they provide extended potential windows in acidic electrolytes (up to 1.5 V) which led to ultrahigh energy densities of 1.5 and 2.2 mWh cm−3for PMo12@PPy and PW12@PPy cells, respectively. Thus, these unique organic-inorganic hybrid symmetric cells displayed extraordinary electrochemical performances far exceeding those of more complex asymmetric systems. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

  • GaN surface states investigated by electrochemical studies

    Winnerl A., Garrido J.A., Stutzmann M. Applied Physics Letters; 110 (10, 101602) 2017. 10.1063/1.4977947.

    Advanced Electronic Materials and Devices

    We present a systematic study of electrochemically active surface states on MOCVD-grown n-type GaN in aqueous electrolytes using cyclic voltammetry and impedance spectroscopy over a wide range of potentials and frequencies. In order to alter the surface states, the GaN samples are either etched or oxidized, and the influence of the surface treatment on the defect-mediated charge transfer to the electrolyte is investigated. Etching in HCl removes substoichiometric GaOx, and leads to a pronounced density of electrochemically active surface states. Oxidation effectively removes these surface states. © 2017 Author(s).

  • Grain boundary-induced variability of charge transport in hydrogenated polycrystalline graphene

    Vargas J.E.B., Falkenberg J.T., Soriano D., Cummings A.W., Brandbyge M., Roche S. 2D Materials; 4 (2, 025009) 2017. 10.1088/2053-1583/aa59de.

    Theoretical and Computational Nanoscience

    Chemical functionalization has proven to be a promising means of tailoring the unique properties of graphene. For example, hydrogenation can yield a variety of interesting effects, including a metal-insulator transition or the formation of localized magnetic moments. Meanwhile, graphene grown by chemical vapor deposition is the most suitable for large-scale production, but the resulting material tends to be polycrystalline. Up to now there has been relatively little focus on how chemical functionalization, and hydrogenation in particular, impacts the properties of polycrystalline graphene. In this work, we use numerical simulations to study the electrical properties of hydrogenated polycrystalline graphene. We find a strong correlation between the spatial distribution of the hydrogen adsorbates and the charge transport properties. Charge transport is weakly sensitive to hydrogenation when adsorbates are confined to the grain boundaries, while a uniform distribution of hydrogen degrades the electronic mobility. This difference stems from the formation of the hydrogen-induced resonant impurity states, which are inhibited when the honeycomb symmetry is locally broken by the grain boundaries. These findings suggest a tunability of electrical transport of polycrystalline graphene through selective hydrogen functionalization, and also have implications for hydrogen-induced magnetization and spin lifetime of this material. © 2017 IOP Publishing Ltd.

  • Graphene Field-Effect Transistors for In Vitro and Ex Vivo Recordings

    Kireev D., Zadorozhnyi I., Qiu T., Sarik D., Brings F., Wu T., Seyock S., Maybeck V., Lottner M., Blaschke B.M., Garrido J., Xie X., Vitusevich S., Wolfrum B., Offenhäusser A. IEEE Transactions on Nanotechnology; 16 (1, 7782310): 140 - 147. 2017. 10.1109/TNANO.2016.2639028.

    Advanced Electronic Materials and Devices

    Recording extracellular potentials from electrogenic cells (especially neurons) is the hallmark destination of modern bioelectronics. While fabrication of flexible and biocompatible in vivo devices via silicon technology is complicated and time-consuming, graphene field-effect transistors (GFETs), instead, can easily be fabricated on flexible and biocompatible substrates. In this work, we compare GFETs fabricated on rigid (SiO2/Si and sapphire) and flexible (polyimide) substrates. The GFETs, fabricated on the polyimide, exhibit extremely large transconductance values, up to 11 mS·V-1, and mobility over 1750 cm2·V-1·s-1. In vitro recordings from cardiomyocyte-like cell culture are performed by GFETs on a rigid transparent substrate (sapphire). Via multichannel measurement, we are able to record and analyze both: difference in action potentials as well as their spatial propagation over the chip. Furthermore, the controllably flexible polyimide-on-steel (PIonS) substrates are able to ex vivo record electrical signals from primary embryonic rat heart tissue. Considering the flexibility of PIonS chips, together with the excellent sensitivity, we open up a new road into graphene-based in vivo biosensing. © 2016 IEEE.

  • Graphene-Based Biosensors: Going Simple

    Morales-Narváez E., Baptista-Pires L., Zamora-Gálvez A., Merkoçi A. Advanced Materials; 29 (7, 1604905) 2017. 10.1002/adma.201604905.

    Nanobioelectronics and Biosensors

    The main properties of graphene derivatives facilitating optical and electrical biosensing platforms are discussed, along with how the integration of graphene derivatives, plastic, and paper can lead to innovative devices in order to simplify biosensing technology and manufacture easy-to-use, yet powerful electrical or optical biosensors. Some crucial issues to be overcome in order to bring graphene-based biosensors to the market are also underscored. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

  • Graphene-based hybrid for enantioselective sensing applications

    Zor E., Morales-Narváez E., Alpaydin S., Bingol H., Ersoz M., Merkoçi A. Biosensors and Bioelectronics; 87: 410 - 416. 2017. 10.1016/j.bios.2016.08.074.

    Nanobioelectronics and Biosensors

    Chirality is a major field of research of chemical biology and is essential in pharmacology. Accordingly, approaches for distinguishing between different chiral forms of a compound are of great interest. We report on an efficient and generic enantioselective sensor that is achieved by coupling reduced graphene oxide with γ-cyclodextrin (rGO/γ-CD). The enantioselective sensing capability of the resulting structure was operated in both electrical and optical mode for of tryptophan enantiomers (D-/L-Trp). In this sense, voltammetric and photoluminescence measurements were conducted and the experimental results were compared to molecular docking method. We gain insight into the occurring recognition mechanism with selectivity toward D- and L-Trp as shown in voltammetric, photoluminescence and molecular docking responses. As an enantioselective solid phase on an electrochemical transducer, thanks to the different dimensional interaction of enantiomers with hybrid material, a discrepancy occurs in the Gibbs free energy leading to a difference in oxidation peak potential as observed in electrochemical measurements. The optical sensing principle is based on the energy transfer phenomenon that occurs between photoexcited D-/L-Trp enantiomers and rGO/γ-CD giving rise to an enantioselective photoluminescence quenching due to the tendency of chiral enantiomers to form complexes with γ-CD in different molecular orientations as demonstrated by molecular docking studies. The approach, which is the first demonstration of applicability of molecular docking to show both enantioselective electrochemical and photoluminescence quenching capabilities of a graphene-related hybrid material, is truly new and may have broad interest in combination of experimental and computational methods for enantiosensing of chiral molecules. © 2016 Elsevier B.V.

  • Heteroepitaxial Beta-Ga2O3 on 4H-SiC for an FET with Reduced Self Heating

    Russell S.A.O., Perez-Tomas A., McConville C.F., Fisher C.A., Hamilton D.P., Mawby P.A., Jennings M.R. IEEE Journal of the Electron Devices Society; 5 (4, 7932063): 256 - 261. 2017. 10.1109/JEDS.2017.2706321.

    Oxide Nanophysics

    A method to improve thermal management of ${\beta }$ -Ga2O3 FETs is demonstrated here via simulation of epitaxial growth on a 4H-SiC substrate. Using a recently published device as a model, the reduction achieved in self-heating allows the device to be driven at higher gate voltages and increases the overall performance. For the same operating parameters an 18% increase in peak drain current and 15% reduction in lattice temperature are observed. Device dimensions may be substantially reduced without detriment to performance and normally off operation may be achieved. © 2013 IEEE.

  • Hierarchical surfaces for enhanced self-cleaning applications

    Fernández A., Francone A., Thamdrup L.H., Johansson A., Bilenberg B., Nielsen T., Guttmann M., Sotomayor Torres C.M., Kehagias N. Journal of Micromechanics and Microengineering; 27 (4, 045020) 2017. 10.1088/1361-6439/aa62bb.

    Phononic and Photonic Nanostructures

    In this study we present a flexible and adaptable fabrication method to create complex hierarchical structures over inherently hydrophobic resist materials. We have tested these surfaces for their superhydrophobic behaviour and successfully verified their self-cleaning properties. The followed approach allow us to design and produce superhydrophobic surfaces in a reproducible manner. We have analysed different combination of hierarchical micro-nanostructures for their application to self-cleaning surfaces. A static contact angle value of 170 with a hysteresis of 4 was achieved without the need of any additional chemical treatment on the fabricated hierarchical structures. Dynamic effects were analysed on these surfaces, obtaining a remarkable self-cleaning effect as well as a good robustness over impacting droplets. © 2017 IOP Publishing Ltd.

  • High-Temperature Electrical and Thermal Aging Performance and Application Considerations for SiC Power DMOSFETs

    Hamilton D.P., Jennings M.R., Perez-Tomas A., Russell S.A.O., Hindmarsh S.A., Fisher C.A., Mawby P.A. IEEE Transactions on Power Electronics; 32 (10, 7776925): 7967 - 7979. 2017. 10.1109/TPEL.2016.2636743.

    Oxide Nanophysics

    The temperature dependence and stability of three different commercially-available unpackaged SiC Dmosfets have been measured. On-state resistances increased to 6 or 7 times their room temperature values at 350 °C. Threshold voltages almost doubled after tens of minutes of positive gate voltage stressing at 300 °C, but approached their original values again after only one or two minutes of negative gate bias stressing. Fortunately, the change in drain current due to these threshold instabilities was almost negligible. However, the threshold approaches zero volts at high temperatures after a high temperature negative gate bias stress. The zero gate bias leakage is low until the threshold voltage reduces to approximately 150 mV, where-after the leakage increases exponentially. Thermal aging tests demonstrated a sudden change from linear to nonlinear output characteristics after 24-100 h air storage at 300 °C and after 570-1000 h in N2 atmosphere. We attribute this to nickel oxide growth on the drain contact metallization which forms a heterojunction p-n diode with the SiC substrate. It was determined that these state-of-the-art SiC mosfet devices may be operated in real applications at temperatures far exceeding their rated operating temperatures. © 1986-2012 IEEE.

  • Hurdles to organic quinone flow cells. Electrode passivation by quinone reduction in acetonitrile Li electrolytes

    Rueda-García D., Dubal D.P., Hugenin F., Gómez-Romero P. Journal of Power Sources; 350: 9 - 17. 2017. 10.1016/j.jpowsour.2017.03.048.

    Novel Energy-Oriented Materials

    The uses of quinones in Redox Flow Batteries (RFBs) has been mainly circumscribed to aqueous solutions (of derivatives with polar groups) despite a larger solubility and wider electrochemical window provided by organic media. The redox mechanism of quinones in protic media is simpler and better known than in aprotic media, where radical species are involved. This paper reports the behaviour of methyl-p-benzoquinone (MBQ) under electrochemical reduction conditions in a LiClO4[sbnd]CH3CN electrolyte and various working electrodes. We detected the reversible generation of a bright green coating on the working electrode and the subsequent formation of a polymer (the nature of which depends on the presence or absence of oxygen). These coatings prevent the regular redox process of methyl-p-benzoquinone from taking place on the surface of the electrode and is generated regardless of the electrode material used or the presence of O2 in solution. In addition to MBQ, the green passivating layer was also found for less sterically hindered quinones such as p-benzoquinone or 1,4-naphthoquinone, but not for anthraquinone. We have also shown the central role of Li+ in the formation of this green layer. This work provides important guidelines for the final use of quinones in RFBs with organic electrolytes. © 2017

  • Hydrogen Activation by Frustrated Lewis Pairs Revisited by Metadynamics Simulations

    Liu L., Lukose B., Ensing B. Journal of Physical Chemistry C; 121 (4): 2046 - 2051. 2017. 10.1021/acs.jpcc.6b09991.

    Frustrated Lewis pairs have great potential as metal-free catalysts, for example, for the activation of molecular hydrogen. However, rational design of improved catalysts is hampered because the catalytic reaction mechanisms still remain largely unclear. In this study, we present a density-functional-theory-based metadynamics study of the hydrogen activation by a typical frustrated Lewis pair, tBu3P/B(C6F5)3. The computed free-energy landscape reveals a different reaction path compared with the ones in the literature. Importantly, we found different roles of the Lewis acid and base centers in the hydrogen activation. The rate-determining step is the hydride transfer to the Lewis acid, and the overall reaction is found to be exothermic once the proton transfer to the Lewis base step is accomplished. © 2017 American Chemical Society.

  • In Situ Determination of the Water Condensation Mechanisms on Superhydrophobic and Superhydrophilic Titanium Dioxide Nanotubes

    Macias-Montero M., Lopez-Santos C., Filippin A.N., Rico V.J., Espinos J.P., Fraxedas J., Perez-Dieste V., Escudero C., Gonzalez-Elipe A.R., Borras A. Langmuir; 33 (26): 6449 - 6456. 2017. 10.1021/acs.langmuir.7b00156.

    Force Probe Microscopy and Surface Nanoengineering

    One-dimensional (1D) nanostructured surfaces based on high-density arrays of nanowires and nanotubes of photoactive titanium dioxide (TiO2) present a tunable wetting behavior from superhydrophobic to superhydrophilic states. These situations are depicted in a reversible way by simply irradiating with ultraviolet light (superhydrophobic to superhydrophilic) and storage in dark. In this article, we combine in situ environmental scanning electron microscopy (ESEM) and near ambient pressure photoemission analysis (NAPP) to understand this transition. These experiments reveal complementary information at microscopic and atomic level reflecting the surface wettability and chemical state modifications experienced by these 1D surfaces upon irradiation. We pay special attention to the role of the water condensation mechanisms and try to elucidate the relationship between apparent water contact angles of sessile drops under ambient conditions at the macroscale with the formation of droplets by water condensation at low temperature and increasing humidity on the nanotubes' surfaces. Thus, for the as-grown nanotubes, we reveal a metastable and superhydrophobic Cassie state for sessile drops that tunes toward water dropwise condensation at the microscale compatible with a partial hydrophobic Wenzel state. For the UV-irradiated surfaces, a filmwise wetting behavior is observed for both condensed water and sessile droplets. NAPP analyses show a hydroxyl accumulation on the as-grown nanotubes surfaces during the exposure to water condensation conditions, whereas the water filmwise condensation on a previously hydroxyl enriched surface is proved for the superhydrophilic counterpart. © 2017 American Chemical Society.

  • Incorporation of Counter Ions in Organic Molecules: New Strategy in Developing Dopant-Free Hole Transport Materials for Efficient Mixed-Ion Perovskite Solar Cells

    Zhang J., Xu B., Yang L., Mingorance A., Ruan C., Hua Y., Wang L., Vlachopoulos N., Lira-Cantú M., Boschloo G., Hagfeldt A., Sun L., Johansson E.M.J. Advanced Energy Materials; 7 (14) 2017. 10.1002/aenm.201602736.

    Nanostructured Materials for Photovoltaic Energy

    Hole transport matertial (HTM) as charge selective layer in perovskite solar cells (PSCs) plays an important role in achieving high power conversion efficiency (PCE). It is known that the dopants and additives are necessary in the HTM in order to improve the hole conductivity of the HTM as well as to obtain high efficiency in PSCs, but the additives can potentially induce device instability and poor device reproducibility. In this work a new strategy to design dopant-free HTMs has been presented by modifying the HTM to include charged moieties which are accompanied with counter ions. The device based on this ionic HTM X44 dos not need any additional doping and the device shows an impressive PCE of 16.2%. Detailed characterization suggests that the incorporated counter ions in X44 can significantly affect the hole conductivity and the homogeneity of the formed HTM thin film. The superior photovoltaic performance for X44 is attributed to both efficient hole transport and effective interfacial hole transfer in the solar cell device. This work provides important insights as regards the future design of new and efficient dopant free HTMs for photovotaics or other optoelectronic applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

  • Inductively coupled remote plasma-enhanced chemical vapor deposition (rPE-CVD) as a versatile route for the deposition of graphene micro- and nanostructures

    Cuxart M.G., Šics I., Goñi A.R., Pach E., Sauthier G., Paradinas M., Foerster M., Aballe L., Fernandez H.M., Carlino V., Pellegrin E. Carbon; 117: 331 - 342. 2017. 10.1016/j.carbon.2017.02.067.

    Force Probe Microscopy and Surface Nanoengineering | Atomic Manipulation and Spectroscopy

    Multiple layers of graphene thin films with micro-crystalline orientation and vertical graphene nano-sheets were grown on different substrates (i.e., polycrystalline nickel foil, Ni(111), highly oriented pyrolytic graphite) using a single-step process based on low-pressure remote Plasma-Enhanced Chemical Vapor Deposition (rPE-CVD). In contrast to previous studies, a novel basic approach to this technique including a new remote inductively coupled RF plasma source has been used to (i) minimize the orientational effect of the plasma electrical fields during the catalyst-free growth of graphene nano-sheets, (ii) warrant for a low graphene defect density via low plasma kinetics, (iii) decouple the dissociation process of the gas from the growth process of graphene on the substrate, (iv) tune the feedstock gas chemistry in view of improving the graphene growth, and (v) reduce the growth temperature as compared to conventional chemical vapor deposition (CVD). In order to study the various aspects of the rPE-CVD graphene growth modes and to assess the characteristics of the resulting graphene layers, Raman spectroscopy, XPS, SEM, and STM were used. The results give evidence for the successful performance of this new rPE-CVD plasma deposition source, that can be combined with in situ UHV-based processess for the production of, e. g., hybrid metal ferromagnet/graphene systems. © 2017 Elsevier Ltd

  • Influence of texture in hybrid carbon-phosphomolybdic acid materials on their performance as electrodes in supercapacitors

    Palomino P., Suarez-Guevara J., Olivares-Marín M., Ruiz V., Dubal D.P., Gómez-Romero P., Tonti D., Enciso E. Carbon; 111: 74 - 82. 2017. 10.1016/j.carbon.2016.09.054.

    Novel Energy-Oriented Materials

    In this paper, phosphomolybdic acid H3PMo12O40 (PMo12) was anchored to four synthetic micro-mesoporous carbons and a commercial one to analyse the relationship between the porous texture of the support, the PMo12 adsorption and the performance of the resulting hybrid materials as electrodes in supercapacitors. The uptake of PMo12 on carbon supports follows a clear correlation with the micropore volume, which implies that PMo12 is mainly adsorbed in microporosity as a consequence of a greater confinement in this kind of pores instead of mesopores. Transmission electron microscopy indicates that the PMo12 adsorbed is homogeneously dispersed in the carbon texture. Finally, the addition of PMo12 to the original carbon electrodes provided capacitances up to 293 F per gram of electrode, substantially larger than the 206–240 F g−1 of the unmodified activated carbon. This result represented an increase of up to 35% in terms of gravimetric energy density and 160% in terms of volumetric energy density, after PMo12 integration into the carbon matrix. © 2016 Elsevier Ltd

  • Inorganic photocatalytic enhancement: Activated RhB Photodegradation by surface modification of SnO2 Nanocrystals with V2 O5-like species

    Epifani M., Kaciulis S., Mezzi A., Altamura D., Giannini C., Díaz R., Force C., Genç A., Arbiol J., Siciliano P., Comini E., Concina I. Scientific Reports; 7 ( 44763) 2017. 10.1038/srep44763.

    Advanced Electron Nanoscopy

    SnO2 nanocrystals were prepared by precipitation in dodecylamine at 100 °C, then they were reacted with vanadium chloromethoxide in oleic acid at 250 °C. The resulting materials were heat-treated at various temperatures up to 650 °C for thermal stabilization, chemical purification and for studying the overall structural transformations. From the crossed use of various characterization techniques, it emerged that the as-prepared materials were constituted by cassiterite SnO2 nanocrystals with a surface modified by isolated V(IV) oxide species. After heat-treatment at 400 °C, the SnO2 nanocrystals were wrapped by layers composed of vanadium oxide (IV-V mixed oxidation state) and carbon residuals. After heating at 500 °C, only SnO2 cassiterite nanocrystals were obtained, with a mean size of 2.8 nm and wrapped by only V2 O5-like species. The samples heat-treated at 500 °C were tested as RhB photodegradation catalysts. At 10-7 M concentration, all RhB was degraded within 1 h of reaction, at a much faster rate than all pure SnO2 materials reported until now. © The Author(s) 2017.

  • Interfacing neurons on carbon nanotubes covered with diamond

    Seyock S., Maybeck V., Scorsone E., Rousseau L., Hébert C., Lissorgues G., Bergonzo P., Offenhäusser A. RSC Advances; 7 (1): 153 - 160. 2017. 10.1039/c6ra20207a.

    Advanced Electronic Materials and Devices

    A recently discovered material, carbon nanotubes covered with diamond (DCNTs) was tested for its suitability in bioelectronics applications. Diamond shows advantages for bioelectronics applications (wide electro chemical window and bioinertness). This study investigates the effect of electrode surface shape (flat or three dimensional) on cell growth and behavior. For comparison, flat nanocrystalline diamond substrates were used. Primary embryonic neurons were grown on top of the structures and neither incorporated the structures nor did they grow in between the single structures. The interface was closely examined using focused ion beam (FIB) and scanning electron microscopy. Of special interest was the interface between cell and substrate. 5% to 25% of the cell membrane adhered to the substrate, which fits the theoretical estimated value. While investigating the conformity of the neurons, it could be observed that the cell membrane attaches to different heights of the tips of the 3D structure. However, the aspect ratio of the structures had no effect on the cell viability. These results let us assume that not more than 25% of cell attachment is needed for the survival of a functional neuronal cell. © The Royal Society of Chemistry.

  • Kondo screening of the spin and orbital magnetic moments of Fe impurities in Cu

    Joly L., Kappler J.-P., Ohresser P., Sainctavit P., Henry Y., Gautier F., Schmerber G., Kim D.J., Goyhenex C., Bulou H., Bengone O., Kavich J., Gambardella P., Scheurer F. Physical Review B; 95 (4, 041108) 2017. 10.1103/PhysRevB.95.041108.

    We use x-ray magnetic circular dichroism to evidence the effect of correlations on the local impurity magnetic moment in an archetypal Kondo system, namely, a dilute Cu:Fe alloy. Applying the sum rules on the Fe L2,3 absorption edges, the evolution of the spin and orbital moments across the Kondo temperature are determined separately. The spin moment presents a crossover from a nearly temperature-independent regime below the Kondo temperature to a paramagneticlike regime above. Conversely, the weak orbital moment shows a temperature-independent behavior in the whole temperature range, suggesting different Kondo screening temperature scales for the spin and orbital moments. © 2017 American Physical Society.

  • Large edge magnetism in oxidized few-layer black phosphorus nanomeshes

    Nakanishi Y., Ishi A., Ohata C., Soriano D., Iwaki R., Nomura K., Hasegawa M., Nakamura T., Katsumoto S., Roche S., Haruyama J. Nano Research; 10 (2): 718 - 728. 2017. 10.1007/s12274-016-1355-8.

    Theoretical and Computational Nanoscience

    The formation and control of a room-temperature magnetic order in two-dimensional (2D) materials is a challenging quest for the advent of innovative magnetic- and spintronic-based technologies. To date, edge magnetism in 2D materials has been experimentally observed in hydrogen (H)-terminated graphene nanoribbons (GNRs) and graphene nanomeshes (GNMs), but the measured magnetization remains far too small to allow envisioning practical applications. Herein, we report experimental evidences of large room-temperature edge ferromagnetism (FM) obtained from oxygen (O)-terminated zigzag pore edges of few-layer black phosphorus (P) nanomeshes (BPNMs). The magnetization values per unit area are ~100 times larger than those reported for H-terminated GNMs, while the magnetism is absent for H-terminated BPNMs. The magnetization measurements and the first-principles simulations suggest that the origin of such a magnetic order could stem from ferromagnetic spin coupling between edge P with O atoms, resulting in a strong spin localization at the edge valence band, and from uniform oxidation of full pore edges over a large area and interlayer spin interaction. Our findings pave the way for realizing high-efficiency 2D flexible magnetic and spintronic devices without the use of rare magnetic elements. [Figure not available: see fulltext.] © 2017, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

  • Large scale flexible solid state symmetric supercapacitor through inexpensive solution processed V2O5 complex surface architecture

    Pandit B., Dubal D.P., Sankapal B.R. Electrochimica Acta; 242: 382 - 389. 2017. 10.1016/j.electacta.2017.05.010.

    Complex nanostructured morphology of V2O5 has been grown on pliable stainless steel substrate (SS) through simple and inexpensive chemical bath deposition (CBD) for all-solid state flexible supercapacitor (SC). The structure and morphology of the synthesized V2O5 thin films revealed the formation of intermixed flakes. High specific capacitance of 735 F g−1 (at scan rate of 1 mV s−1) of V2O5 through liquid configuration motivated us to form complete flexible all-solid state symmetric supercapacitor (FASC) device. Remarkable specific capacitance of 358 F g−1. With 1.8 V wide potential window and high value of capacitive retention of 88% over 1000 cycles has been achieved for FASC. Furthermore, the origin of capacitive behavior from dual contributions of surface-controlled and diffusion-controlled charge components has been evaluated to identify the dominating nature in electrochemical reactions. As practical applicability, pliability of electrode has been tested at 175° bending angle along with the integration to large scale electrode dimension (11 ×4 cm2). © 2017 Elsevier Ltd

  • Lateral Magnetically Modulated Multilayers by Combining Ion Implantation and Lithography

    Menéndez E., Modarresi H., Petermann C., Nogués J., Domingo N., Liu H., Kirby B.J., Mohd A.S., Salhi Z., Babcock E., Mattauch S., Van Haesendonck C., Vantomme A., Temst K. Small; 13 (11, 1603465) 2017. 10.1002/smll.201603465.

    Oxide Nanophysics | Magnetic Nanostructures

    The combination of lithography and ion implantation is demonstrated to be a suitable method to prepare lateral multilayers. A laterally, compositionally, and magnetically modulated microscale pattern consisting of alternating Co (1.6 µm wide) and Co-CoO (2.4 µm wide) lines has been obtained by oxygen ion implantation into a lithographically masked Au-sandwiched Co thin film. Magnetoresistance along the lines (i.e., current and applied magnetic field are parallel to the lines) reveals an effective positive giant magnetoresistance (GMR) behavior at room temperature. Conversely, anisotropic magnetoresistance and GMR contributions are distinguished at low temperature (i.e., 10 K) since the O-implanted areas become exchange coupled. This planar GMR is principally ascribed to the spatial modulation of coercivity in a spring-magnet-type configuration, which results in 180° Néel extrinsic domain walls at the Co/Co-CoO interfaces. The versatility, in terms of pattern size, morphology, and composition adjustment, of this method offers a unique route to fabricate planar systems for, among others, spintronic research and applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

  • Ligand and solvent effects in the formation and self-assembly of a metallosupramolecular cage

    Adarsh N.N., Chakraborty A., Tarrés M., Dey S., Novio F., Chattopadhyay B., Ribas X., Ruiz-Molina D. New Journal of Chemistry; 41 (3): 1179 - 1185. 2017. 10.1039/C6NJ03456J.

    Nanostructured Functional Materials

    Two bis-pyridyl-bis-urea ligands namely N,N′-bis-(3-pyridyl)diphenylmethylene-bis-urea (L1) and N,N′-bis-(3-picolyl)diphenylmethylene-bis-urea (L2) have been reacted with a Cu(ii) salt resulting in the formation of a metallosupramolecular cage [{Cu2(μ-L1)4(DMSO)2(H2O)2}·SO4·X] (1) and a one-dimensional coordination polymer [{Cu(1)(μ-L2)2(H2O)2}{Cu(2)(μ-L2)2(H2O)2}·2SO4·9H2O·X]n (2) (where DMSO = dimethylsulfoxide, and X = disordered lattice included solvent molecules), respectively. The single crystal structures of 1 and 2 are discussed in the context of the effect of the ligands, particularly the hydrogen bonding functionality of the ligand, on the supramolecular structural diversities observed in these metal organic compounds. The supramolecular packing of 1 is clearly influenced by the nature of the solvent and ligand used; mixtures of DMSO/MeOH or DMSO/H2O lead to the formation of blue crystals or a hydrogel, respectively. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.

  • Liposome-based immunotherapy against autoimmune diseases: Therapeutic effect on multiple sclerosis

    Pujol-Autonell I., Mansilla M.-J., Rodriguez-Fernandez S., Cano-Sarabia M., Navarro-Barriuso J., Ampudia R.-M., Rius A., Garcia-Jimeno S., Perna-Barrull D., Caceres E.M., Maspoch D., Vives-Pi M. Nanomedicine; 12 (11): 1231 - 1242. 2017. 10.2217/nnm-2016-0410.

    Supramolecular NanoChemistry and Materials

    Based on the ability of apoptosis to induce immunological tolerance, liposomes were generated mimicking apoptotic cells, and they arrest autoimmunity in Type 1 diabetes. Our aim was to validate the immunotherapy in other autoimmune disease: multiple sclerosis. Materials & methods: Phosphatidylserine-rich liposomes were loaded with disease-specific autoantigen. Therapeutic capability of liposomes was assessed in vitro and in vivo. Results: Liposomes induced a tolerogenic phenotype in dendritic cells, and arrested autoimmunity, thus decreasing the incidence, delaying the onset and reducing the severity of experimental disease, correlating with an increase in a probably regulatory CD25+ FoxP3- CD4+ T-cell subset. Conclusion: This is the first work that confirms phosphatidylserine-liposomes as a powerful tool to arrest multiple sclerosis, demonstrating its relevance for clinical application. © 2017 Future Medicine Ltd.

  • Low-pressure RF remote plasma cleaning of carbon-contaminated B4C-coated optics

    Moreno Fernández H., Thomasset M., Sauthier G., Rogler D., Dietsch R., Barrett R., Carlino V., Pellegrin E. Proceedings of SPIE - The International Society for Optical Engineering; 10236 ( 102360E) 2017. 10.1117/12.2269374.

    Boron carbide (B4C)-due to its exceptional mechanical properties-is one of the few existing materials that can withstand the extremely high brilliance of the photon beam from free electron lasers (FELs) and is thus of considerable interest for optical applications in this field. However, as in the case of many other optics operated at modern accelerator-, plasma-, or laser-based light source facilities, B4C-coated optics are subject to ubiquitous carbon contaminations. These contaminations-that are presumably produced via cracking of CHx and CO2 molecules by photoelectrons emitted from the optical components-represent a serious issue for the operation of the pertinent high performance beamlines due to a severe reduction of photon flux and beam coherence, not necessarily restricted to the photon energy range of the carbon K-edge. Thus, a variety of B4C cleaning technologies have been developed at different laboratories with varying success [1]. Here, we present a study regarding the low-pressure RF plasma cleaning of a series of carbon-contaminated B4C test samples via an inductively coupled O2/Ar and Ar/H2 remote RF plasma produced using the IBSS GV10x plasma source following previous studies using the same RF plasma source [2, 3]. Results regarding the chemistry, morphology as well as other aspects of the B4C optical coatings and surfaces before and after the plasma cleaning process are reported. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.

  • Low-Temperature Growth of Axial Si/Ge Nanowire Heterostructures Enabled by Trisilane

    Hui H.Y., De La Mata M., Arbiol J., Filler M.A. Chemistry of Materials; 29 (8): 3397 - 3402. 2017. 10.1021/acs.chemmater.6b03952.

    Advanced Electron Nanoscopy

    Axial Si/Ge heterostructure nanowires, despite their promise in applications ranging from electronics to thermal transport, remain notoriously difficult to synthesize. Here, we grow axial Si/Ge heterostructures at low temperatures using a Au catalyst with a combination of trisilane and digermane. This approach yields, as determined with detailed electron microscopy characterization, arrays of epitaxial Si/Ge nanowires with excellent morphologies and purely axial composition profiles. Our data indicate that heterostructure formation can occur via the vapor-liquid-solid or vapor-solid-solid mechanism. These findings highlight the importance of precursor chemistry in semiconductor nanowire synthesis and open the door to Si/Ge nanowires with programmable quantum domains. © 2017 American Chemical Society.

  • Magnetic nanoparticle-molecular imprinted polymer: A new impedimetric sensor for tributyltin detection

    Zamora-Gálvez A., Mayorga-Matinez C.C., Parolo C., Pons J., Merkoçi A. Electrochemistry Communications; 82: 6 - 11. 2017. 10.1016/j.elecom.2017.07.007.

    Nanobioelectronics and Biosensors

    Recently, molecular imprinted polymers (MIPs) were extensively used for separation and identification of specific molecules, replacing expensive and unstable biological receptors. Nonetheless, their application in electrochemical sensors has not been sufficiently explored. Here we report the use of a MIP as a specific receptor in a new highly sensitive tributyltin (TBT) electrochemical sensor. The sensor combines the specificity, pre-concentration capability and robustness of molecular imprinted polymer attached onto magnetic nanoparticles with the quantitative outputs of impedimetric measurements. The proposed device detects TBT in a concentration range of 5 pM to 5 μM with a low limit of detection (5.37 pM), which is lower than the one recommended for TBT in sea water by the US Environmental Protection Agency (EPA). We believe that this new electrochemical sensor can play an important role in the monitoring of the quality of sea and fresh waters worldwide. © 2017 Elsevier B.V.

  • Magnetically-actuated mesoporous nanowires for enhanced heterogeneous catalysis

    Serrà A., Grau S., Gimbert-Suriñach C., Sort J., Nogués J., Vallés E. Applied Catalysis B: Environmental; 217: 81 - 91. 2017. 10.1016/j.apcatb.2017.05.071.

    Nanostructured Functional Materials | Magnetic Nanostructures

    We study the optimization of the catalytic properties of entirely magnetic Co–Pt compact and mesoporous nanowires of different diameters (25–200 nm) by using magnetic actuation. The nanowires are a single-entity, robust, magnetic-catalyst with a huge catalytically-active surface area. We show that apart from conventional parameters, like the size and morphology of the nanowires, other factors can be optimized to enhance their catalytic activity. In particular, given the magnetic character of the nanowires, rotating magnetic fields are a very powerful approach to boost the performance of the catalyst. In particular, the magnetic field induces them to act as nano-stirrers, improving the local flow of material towards the active sites of the catalyst. We demonstrate the versatility of the procedure by optimizing (i) the degradation of different types of pollutants (4-nitrophenol and methylene blue) and (ii) hydrogen production. For example, by using as little as 0.1 mg mL−1 of 25 nm wide Co–Pt mesoporous nanowires (with ∼3 nm pore size) as catalysts, kinetic normalized constants knor as high as 20,667 and 21,750 s−1 g−1 for 4-nitrophenol and methylene blue reduction, respectively, are obtained. In addition, activity values for hydrogen production from borohydride are as high as 25.0 L H2 g−1 min−1, even at room temperature. These values outperform any current state-of-the-art proposed catalysis strategies for water remediation reactions by at least 10-times and are superior to most advanced approaches to generate hydrogen from borohydride. The recyclability of the nanowires together with the simplicity of the synthetic method makes this approach (using not only Co–Pt, but also other mesoporous magnetic catalysts) very appealing for very diverse types of catalytic applications. © 2017 Elsevier B.V.

  • Mapping brain activity with flexible graphene micro-transistors

    Blaschke B.M., Tort-Colet N., Guimerà-Brunet A., Weinert J., Rousseau L., Heimann A., Drieschner S., Kempski O., Villa R., Sanchez-Vives M.V., Garrido J.A. 2D Materials; 4 (2, 025040) 2017. 10.1088/2053-1583/aa5eff.

    Advanced Electronic Materials and Devices

    Establishing a reliable communication interface between the brain and electronic devices is of paramount importance for exploiting the full potential of neural prostheses. Current microelectrode technologies for recording electrical activity, however, evidence important shortcomings, e.g. challenging high density integration. Solution-gated field-effect transistors (SGFETs), on the other hand, could overcome these shortcomings if a suitable transistor material were available. Graphene is particularly attractive due to its biocompatibility, chemical stability, flexibility, low intrinsic electronic noise and high charge carrier mobilities. Here, we report on the use of an array of flexible graphene SGFETs for recording spontaneous slow waves, as well as visually evoked and also pre-epileptic activity in vivo in rats. The flexible array of graphene SGFETs allows mapping brain electrical activity with excellent signal-to-noise ratio (SNR), suggesting that this technology could lay the foundation for a future generation of in vivo recording implants. © 2017 IOP Publishing Ltd.

  • Maximizing Exchange Bias in Co/CoO Core/Shell Nanoparticles by Lattice Matching between the Shell and the Embedding Matrix

    González J.A., Andrés J.P., López Antón R., De Toro J.A., Normile P.S., Muniz P., Riveiro J.M., Nogués J. Chemistry of Materials; 29 (12): 5200 - 5206. 2017. 10.1021/acs.chemmater.7b00868.

    Magnetic Nanostructures

    The exchange bias properties of 5 nm Co/CoO ferromagnetic/antiferromagnetic core/shell nanoparticles, highly dispersed in a CuxO matrix, have been optimized by matching the lattice parameter of the matrix with that of the CoO shell. Exchange bias and coercivity fields as large as HE = 7780 Oe and HC = 6950 Oe are linked to the presence of a Cu2O matrix (0.3% lattice mismatch with respect to the shells). The small mismatch between Cu2O and CoO plays a dual role: it (i) structurally stabilizes the CoO and (ii) favors the existence of a large amount of uncompensated moments in the shell that enhance the exchange bias effects. The results indicate that lattice matching may be a very efficient way to improve the exchange bias properties of core/shell nanoparticles, paving the way to novel approaches to tune their magnetic properties. © 2017 American Chemical Society.

  • Metamirrors Based on Arrays of Silicon Nanowires with Height Gradients

    Otte M.A., Garcia-Martin A., Borrise X., Sepulveda B. Advanced Optical Materials; 5 (4, 1600933) 2017. 10.1002/adom.201600933.

    Magnetic Nanostructures

    [No abstract available]

  • Microencapsulation with alginate/CaCO 3: A strategy for improved phage therapy

    Colom J., Cano-Sarabia M., Otero J., Aríñez-Soriano J., Cortés P., Maspoch D., Llagostera M. Scientific Reports; 7 ( 41441) 2017. 10.1038/srep41441.

    Supramolecular NanoChemistry and Materials

    Bacteriophages are promising therapeutic agents that can be applied to different stages of the commercial food chain. In this sense, bacteriophages can be orally administered to farm animals to protect them against intestinal pathogens. However, the low pH of the stomach, the activities of bile and intestinal tract enzymes limit the efficacy of the phages. This study demonstrates the utility of an alginate/CaCO3 encapsulation method suitable for bacteriophages with different morphologies and to yield encapsulation efficacies of ∼100%. For the first time, a cocktail of three alginate/CaCO3-encapsulated bacteriophages was administered as oral therapy to commercial broilers infected with Salmonella under farm-like conditions. Encapsulation protects the bacteriophages against their destruction by the gastric juice. Phage release from capsules incubated in simulated intestinal fluid was also demonstrated, whereas encapsulation ensured sufficient intestinal retention of the phages. Moreover, the small size of the capsules (125-150 μm) enables their use in oral therapy and other applications in phage therapy. This study evidenced that a cocktail of the three alginate/CaCO3-encapsulated bacteriophages had a greater and more durable efficacy than a cocktail of the corresponding non-encapsulated phages in as therapy in broilers against Salmonella, one of the most common foodborne pathogen. © 2017 The Author(s).

  • Mimics of microstructures of Ni substituted Mn1−xNixCo2O4 for high energy density asymmetric capacitors

    Tamboli M.S., Dubal D.P., Patil S.S., Shaikh A.F., Deonikar V.G., Kulkarni M.V., Maldar N.N., Inamuddin, Asiri A.M., Gomez-Romero P., Kale B.B., Patil D.R. Chemical Engineering Journal; 307: 300 - 310. 2017. 10.1016/j.cej.2016.08.086.

    Novel Energy-Oriented Materials

    The preparation of nanostructured hierarchical Mn1−xNixCo2O4 metal oxides as efficient supercapacitors of different structures and configurations especially for the miniaturized electronics is still a challenge. In this context, we report template free facile hydrothermal synthesis of hierarchical nanostructured Mn1−xNixCo2O4 with excellent supercapacitive performance. Significantly, the morphology of pure MnCo2O4 transformed from 3D microcubes to 1D nanowires with incorporation of Ni. The electrochemical study shows highest specific capacitance i.e. 1762 F/g for Mn0.4Ni0.6Co2O4 with high cycling stability of 89.2% which is much higher than pristine MnCo2O4 and NiCo2O4. Later, asymmetric capacitor has been fabricated successfully using Mn0.4Ni0.6Co2O4 nanowires as positive electrode and activated carbon (AC) as negative electrode in a KOH aqueous electrolyte. An asymmetric cell could be cycled reversibly in the high-voltage range of 0–1.5 V and displays intriguing performances with a specific capacitance of 112.8 F/g (6.87 F/cm3) and high energy density of 35.2 Wh/kg (2.1 mWh/cm3). Importantly, this asymmetric capacitor device exhibits an excellent long cycle life along with 83.2% specific capacitance retained after 2000 cycles. © 2016 Elsevier B.V.

  • Modeling the Optical Responses of Noble Metal Nanoparticles Subjected to Physicochemical Transformations in Physiological Environments: Aggregation, Dissolution and Oxidation

    Piella J., Bastús N.G., Puntes V. Zeitschrift fur Physikalische Chemie; 231 (1): 33 - 50. 2017. 10.1515/zpch-2016-0874.

    Inorganic Nanoparticles

    Herein, we study how optical properties of colloidal dispersions of noble metal nanoparticles (Au and Ag) are affected by processes such as aggregation and oxidative dissolution. The optical contributions of these processes to the extinction spectra in the UV-vis region are often overlapped, making difficult its interpretation. In this regard, modeling the UV-vis spectra (in particular absorbance curve, peaks position, intensity and full width at half maximum-FWHM) of each process separately offers a powerful tool to identify the transformation of NPs under relevant and complex scenarios, such as in biological media. The proper identification of these transformations is crucial to understand the biological effects of the NPs. © 2017 Walter de Gruyter GmbH, Berlin/Boston.

  • Morphological modification of CdSe0.6Te0.4 nanostructures by electron irradiation and the effect on photoelectrochemical cells

    Shinde S.K., Ghodake G.S., Dubal D.P., Dhaygude H.D., Kim D.-Y., Rath M.C., Fulari V.J. Journal of Materials Science: Materials in Electronics; 28 (2): 1976 - 1984. 2017. 10.1007/s10854-016-5754-0.

    Novel Energy-Oriented Materials

    Morphologically well-ordered synthesis of nanomaterials by modification simple and cost effective. Electron irradiation is a promising pathway to develop various nanostructured materials. We report on the successful fabrication of hierarchical CdSe0.6Te0.4 nanostructures (nanonests, nanobrick-like small spheres with hybrid nanostructure, marigold, and nanoflowers) by electron beam irradiation in electrodeposition. These CdSe0.6Te0.4 nanostructures were employed as electrode material in solar cells, and the relationship between photoelectrochemical properties and CdSe0.6Te0.4 nanostructures was investigated, and showed that the photoelectrochemical properties strongly depend on CdSe0.6Te0.4 nanostructure morphology. The power conversion efficiency for nanonests, nanobrick-like small spheres with hybrid nanostructure, marigold, and nanoflowers of CdSe0.6Te0.4 were 0.88, 0.71, 1.03, and 0.94 %, respectively. © 2016, Springer Science+Business Media New York.

  • Multi-scale analysis of the diffusion barrier layer of gadolinia-doped ceria in a solid oxide fuel cell operated in a stack for 3000 h

    Morales M., Miguel-Pérez V., Tarancón A., Slodczyk A., Torrell M., Ballesteros B., Ouweltjes J.P., Bassat J.M., Montinaro D., Morata A. Journal of Power Sources; 344: 141 - 151. 2017. 10.1016/j.jpowsour.2017.01.109.

    Electron Microscopy Division

    The state-of-the-art materials for SOFCs are yttria-stabilized zirconia as electrolyte and lanthanum strontium cobalt ferrite as cathode. However, the formation of insulating phases between them requires the use of diffusion barriers, typically made of gadolinia doped ceria. The study of the stability of this layer during the fabrication and in operando is currently one of the major goals of the SOFC industry. In this work, the cation inter-diffusion at the cathode/barrier layer/electrolyte region is analysed for an anode-supported cell industrially fabricated by conventional techniques, assembled in a short-stack and tested under real operation conditions for 3000 h. A comprehensive study of this cell, and an equivalent non-operated one, is performed in order to understand the inter-diffusion mechanisms with possible effects on the final performance. The analyses evidence that the cation diffusion is occurring during the fabrication process. Despite the significant diffusion of Ce,Gd, Zr, Y and Sr cations, the formation of typically reported CGO-YSZ solid solution is not observed while the presence of isolated grains of SrZrO3is proved. All in all, this study presents new insights into the stability of the typically employed diffusion barriers for solid oxide cells that will guide future strategies to improve their performance and durability. © 2017 Elsevier B.V.

  • Multiscale modeling of spin transport across a diffuse interface

    Chureemart J., Cuadrado R., Chureemart P., Chantrell R.W. Journal of Magnetism and Magnetic Materials; 443: 287 - 292. 2017. 10.1016/j.jmmm.2017.07.085.

    We present multiscale calculations to describe the spin transport behavior of the Co/Cu bilayer structure including the effect of the interface. The multiscale approach introduces the connection between the ab initio calculation used to describe the electronic structure of the system and the generalized spin accumulation model employed to describe the spin transport behavior. We have applied our model to atomically smooth and diffuse interfaces. The results demonstrate the huge importance of the use of first principle calculations, not only due to the interfacial coordinates optimization but also the magnetic and electronic properties obtained through the electronic structure. The system including the effect of interface with and without the charge fluctuation are studied. The results indicate that changes of electronic structure at the Co/Cu interface give rise to an interfacial resistance distributed over several atomic planes, similar to the effect of interface diffusion. We argue that even atomically smooth Co/Cu interfaces have properties analogous to a diffuse interface due to the variation of electronic structure at the interface. © 2017 The Authors

  • Nanomaterials-Based Platforms for Environmental Monitoring

    Pino F., Mayorga-Martinez C.C., Merkoçi A. Comprehensive Analytical Chemistry; 2017. 10.1016/bs.coac.2017.06.002.

    Nanobioelectronics and Biosensors

    This chapter reviews the latest development of new nanomaterials-based biosensing platforms for environmental monitoring. In particular, we focus our attention in the analysis of different electrochemical analytical systems reported in the last 10. years. Various platforms will be described, pointing out their advantages and also the possible disadvantages. Biosensing platforms are becoming useful devices for environmental monitoring in particular for the use as screening tests for in situ measurement. Some of them are even being commercialized for detection of pollutants like the ones for the detection of heavy metals in different water samples. At the same time the recent years have shown development in the preparation, functionalization and characterisation of new nanomaterials. The new biosensing platforms made using these materials, given the improved analytical performance, could nowadays be an alternative to standard analytical instrumentation for in-field applications. For better understanding of these new electrochemical devices we discuss different nanomaterials (metal nanoparticles, carbon nanotubes, quantum dot and graphene) used not only for the modification of the electrode surface for enhancing the transfer of charge but also as carriers/supporting matrix of the biological recognition element (e.g., enzyme, antibody). The employed nanomaterials have clearly improved the effectiveness of the biosensing in addition of offering also new detection alternatives for various pollutants present in the environment. © 2017 Elsevier B.V.

  • Nanophotonic interferometric immunosensors for label-free and real-time monitoring of chemical contaminants in marine environment

    Chocarro-Ruiz B., Herranz S., Fernández Gavela A., Lechuga L.M. Proceedings of SPIE - The International Society for Optical Engineering; 10215 ( 1021503) 2017. 10.1117/12.2256982.

    NanoBiosensors and Bioanalytical Applications

    With the aim to prevent the oceans ecosystems degradation, there is an urgent need to develop portable sensing tools able to operate directly in the environment, avoiding the transportation of the ocean samples to analytical laboratories. To achieve this long-term objective, we describe here the work carried out to develop and characterize a multiplexed photonic immunosensor for the direct analysis of toxic chemical targets in marine samples. We have employed immunosensors based on photonic Bimodal Waveguide (BiMW) interferometric devices fabricated in silicon technologies combined with specific receptors and antibodies for the targeted chemical targets. Several procedures for the functionalization of the Si3N4 sensor surfaces have been evaluated based on wet silanization methods and further covalent receptor immobilization. The developed immunosensors, based on competitive inhibition assays, show LODs at μg/L or ng/L levels, depending on the analyzed chemical target. © 2017 SPIE.

  • Nanosecond Laser-Assisted Nitrogen Doping of Graphene Oxide Dispersions

    Kepić D., Sandoval S., Pino Á.P.D., György E., Cabana L., Ballesteros B., Tobias G. ChemPhysChem; 18 (8): 935 - 941. 2017. 10.1002/cphc.201601256.

    Electron Microscopy Division

    N-doped reduced graphene oxide (RGO) has been prepared in bulk form by laser irradiation of graphene oxide (GO) dispersed in an aqueous solution of ammonia. A pulsed Nd:YAG laser with emission wavelengths in the infrared (IR) 1064 nm, visible (Vis) 532 nm, and ultraviolet (UV) 266 nm spectral regions was employed for the preparation of the N-doped RGO samples. Regardless of the laser energy employed, the resulting material presents a higher fraction of pyrrolic nitrogen compared to nitrogen atoms in pyridinic and graphitic coordination. Noticeably, whereas increasing the laser fluence of UV and Vis wavelengths results in an increase in the total amount of nitrogen, up to 4.9 at. % (UV wavelength at 60 mJ cm−2 fluence), the opposite trend is observed when the GO is irradiated in ammonia solution through IR processing. The proposed laser-based methodology allows the bulk synthesis of N-doped reduced graphene oxide in a simple, fast, and cost efficient manner. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

  • Nanostructured graphene for spintronics

    Gregersen Sø.S., Power S.R., Jauho A.-P. Physical Review B; 95 (12, 121406) 2017. 10.1103/PhysRevB.95.121406.

    Zigzag edges of the honeycomb structure of graphene exhibit magnetic polarization, making them attractive as building blocks for spintronic devices. Here, we show that devices with zigzag-edged triangular antidots perform essential spintronic functionalities, such as spatial spin splitting or spin filtering of unpolarized incoming currents. Near-perfect performance can be obtained with optimized structures. The device performance is robust against substantial disorder. The gate-voltage dependence of transverse resistance is qualitatively different for spin-polarized and spin-unpolarized devices, and can be used as a diagnostic tool. Importantly, the suggested devices are feasible within current technologies. © 2017 American Physical Society.

  • Nanostructured mixed transition metal oxides for high performance asymmetric supercapacitors: Facile synthetic strategy

    Tajik S., Dubal D.P., Gomez-Romero P., Yadegari A., Rashidi A., Nasernejad B., Inamuddin, Asiri A.M. International Journal of Hydrogen Energy; 42 (17): 12384 - 12395. 2017. 10.1016/j.ijhydene.2017.03.117.

    Novel Energy-Oriented Materials

    Exceptionally simple and cost-effective solid-state method is reported for the synthesis of different mixed transition metal oxides (MTMOs) including FeCo2O4, MnCo2O4 and ZnCo2O4 with unique nanostructures. The morphological analysis show that MTMOs possess distinct nanostructures such as tetragonal, spherical nanoparticles and hexagonal nanosheets. Furthermore, these MTMOs showed excellent supercapacitive properties with specific capacitances of 660–1263 F/g at current density of 2 A/g. Asymmetric capacitor was fabricated with FeCo2O4 as positive and activated carbon as negative electrode which exhibits a specific capacitance of 88 F/g with energy density of 24 Wh/kg (1.1 mWh/cm3) and cycle life (93%) over 5000 cycles. © 2017 Hydrogen Energy Publications LLC

  • Nonlinear dynamics and chaos in an optomechanical beam

    Navarro-Urrios D., Capuj N.E., Colombano M.F., Garciá P.D., Sledzinska M., Alzina F., Griol A., Martínez A., Sotomayor-Torres C.M. Nature Communications; 8 ( 14965) 2017. 10.1038/ncomms14965.

    Phononic and Photonic Nanostructures

    Optical nonlinearities, such as thermo-optic mechanisms and free-carrier dispersion, are often considered unwelcome effects in silicon-based resonators and, more specifically, optomechanical cavities, since they affect, for instance, the relative detuning between an optical resonance and the excitation laser. Here, we exploit these nonlinearities and their intercoupling with the mechanical degrees of freedom of a silicon optomechanical nanobeam to unveil a rich set of fundamentally different complex dynamics. By smoothly changing the parameters of the excitation laser we demonstrate accurate control to activate two- A nd four-dimensional limit cycles, a period-doubling route and a six-dimensional chaos. In addition, by scanning the laser parameters in opposite senses we demonstrate bistability and hysteresis between two- A nd four-dimensional limit cycles, between different coherent mechanical states and between four-dimensional limit cycles and chaos. Our findings open new routes towards exploiting silicon-based optomechanical photonic crystals as a versatile building block to be used in neurocomputational networks and for chaos-based applications. © 2017 The Author(s).

  • On the persistence of polar domains in ultrathin ferroelectric capacitors

    Zubko P., Lu H., Bark C.-W., Martí X., Santiso J., Eom C.-B., Catalan G., Gruverman A. Journal of Physics Condensed Matter; 29 (28, 284001) 2017. 10.1088/1361-648X/aa73c3.

    Oxide Nanophysics | Nanomaterials Growth Division

    The instability of ferroelectric ordering in ultra-thin films is one of the most important fundamental issues pertaining realization of a number of electronic devices with enhanced functionality, such as ferroelectric and multiferroic tunnel junctions or ferroelectric field effect transistors. In this paper, we investigate the polarization state of archetypal ultrathin (several nanometres) ferroelectric heterostructures: epitaxial single-crystalline BaTiO3 films sandwiched between the most habitual perovskite electrodes, SrRuO3, on top of the most used perovskite substrate, SrTiO3. We use a combination of piezoresponse force microscopy, dielectric measurements and structural characterization to provide conclusive evidence for the ferroelectric nature of the relaxed polarization state in ultrathin BaTiO3 capacitors. We show that even the high screening efficiency of SrRuO3 electrodes is still insufficient to stabilize polarization in SrRuO3/BaTiO3/SrRuO3 heterostructures at room temperature. We identify the key role of domain wall motion in determining the macroscopic electrical properties of ultrathin capacitors and discuss their dielectric response in the light of the recent interest in negative capacitance behaviour. © 2017 IOP Publishing Ltd.

  • One-Pot Synthesis of Cationic Gold Nanoparticles by Differential Reduction

    Sperling R.A., Garciá-Fernández L., Ojea-Jiménez I., Piella J., Bastús N.G., Puntes V. Zeitschrift fur Physikalische Chemie; 231 (1): 7 - 18. 2017. 10.1515/zpch-2016-0864.

    Inorganic Nanoparticles

    The size-controlled synthesis of cationic particles by differential reduction of HAuCl4 precursor in the presence of NaBH4 and 1-aminoundecane-12-thiol (AUT) is reported. The number of seed particles is determined by the fraction of the initially Au precursor reduced by NaBH4 present in the reaction mixture, which are then grown larger by the AUT, acting as both weak reducing agent and stabilizing surfactant. By this methodology, size controlled synthesis is achieved in a two-step one-pot synthesis at room temperature. © 2017 Walter de Gruyter GmbH, Berlin/Boston.

  • Optomechanical coupling in the Anderson-localization regime

    García P.D., Bericat-Vadell R., Arregui G., Navarro-Urrios D., Colombano M., Alzina F., Sotomayor-Torres C.M. Physical Review B; 95 (11, 115129) 2017. 10.1103/PhysRevB.95.115129.

    Phononic and Photonic Nanostructures

    Optomechanical crystals, purposely designed and fabricated semiconductor nanostructures, are used to enhance the coupling between the electromagnetic field and the mechanical vibrations of matter at the nanoscale. However, in real optomechanical crystals, imperfections open extra channels where the transfer of energy is lost, reducing the optomechanical coupling efficiency. Here, we quantify the role of disorder in a paradigmatic one-dimensional optomechanical crystal with full phononic and photonic band gaps. We show how disorder can be exploited as a resource to enhance the optomechanical coupling beyond engineered structures, thus providing a new tool set for optomechanics. © 2017 American Physical Society.

  • Oxygen Reduction Mechanisms in Nanostructured La0.8Sr0.2MnO3 Cathodes for Solid Oxide Fuel Cells

    Sacanell J., Hernández Sánchez J., Rubio López A.E., Martinelli H., Siepe J., Leyva A.G., Ferrari V., Juan D., Pruneda M., Mejía Gómez A., Lamas D.G. Journal of Physical Chemistry C; 121 (12): 6533 - 6539. 2017. 10.1021/acs.jpcc.7b00627.

    In this work we outline the mechanisms contributing to the oxygen reduction reaction in nanostructured cathodes of La0.8Sr0.2MnO3 (LSM) for Solid Oxide Fuel Cells (SOFC). These cathodes, developed from LSM nanostructured tubes, can be used at lower temperatures compared to microstructured ones, and this is a crucial fact to avoid the degradation of the fuel cell components. This reduction of the operating temperatures stems mainly from two factors: (i) the appearance of significant oxide ion diffusion through the cathode material in which the nanostructure plays a key role and (ii) an optimized gas phase diffusion of oxygen through the porous structure of the cathode, which becomes negligible. A detailed analysis of our Electrochemical Impedance Spectroscopy supported by first-principles calculations point toward an improved overall cathodic performance driven by a fast transport of oxide ions through the cathode surface. (Figure Presented). © 2017 American Chemical Society.

  • Paper strip-embedded graphene quantum dots: A screening device with a smartphone readout

    Álvarez-DIduk R., Orozco J., Merkoçi A. Scientific Reports; 7 (1, 976) 2017. 10.1038/s41598-017-01134-3.

    Nanobioelectronics and Biosensors

    Simple, inexpensive and rapid sensing systems are very demanded for a myriad of uses. Intrinsic properties of emerging paper-based analytical devices have demonstrated considerable potential to fulfill such demand. This work reports an easy-to-use, low cost, and disposable paper-based sensing device for rapid chemical screening with a smartphone readout. The device comprises luminescent graphene quantum dots (GQDs) sensing probes embedded into a nitrocellulose matrix where the resonance energy transfer phenomenon seems to be the sensing mechanism. The GQDs probes were synthesized from citric acid by a pyrolysis procedure, further physisorbed and confined into small wax-traced spots on the nitrocellulose substrate. The GQDs were excited by an UV LED, this, is powered by a smartphone used as both; energy source and imaging capture. The LED was contained within a 3D-printed dark chamber that isolates the paper platform from external light fluctuations leading to highly reproducible data. The cellulose-based device was proven as a promising screening tool for phenols and polyphenols in environmental and food samples, respectively. It opens up new opportunities for simple and fast screening of organic compounds and offers numerous possibilities for versatile applications. It can be especially useful in remote settings where sophisticated instrumentation is not always available. © 2017 The Author(s).

  • Partial oxidation in a dense phase sub-monolayer of Fe-phthalocyanine on Ag(110)

    Bartolomé E., Bartolomé J., Sedona F., Herrero-Albillos J., Lobo J., Piantek M., García L.M., Panighel M., Mugarza A., Sambi M., Bartolomé F. Solid State Phenomena; 257: 219 - 222. 2017. 10.4028/www.scientific.net/SSP.257.219.

    Atomic Manipulation and Spectroscopy

    In this contribution we report on the structural and magnetic changes along a catalytic cycle of a new dense, “quasi-squared” FePc submonolayer phase (R3) evaporated on Ag(110). X-ray magnetic circular dichroism (XMCD) experiments at the Fe L2,3 edge were performed on four samples: the as-evaporated phase (R3), two differently oxygenated samples (OX1 and OX2) and the annealed phase (ANN). It is concluded that all characterized phases display planar anisotropy, and the values of mseff/nh are one order of magnitude larger than mL/nh. By oxidation, the isotropic moment increases from 7.2 x 10-2 μB/hole to 1.8 x 10-1 μB/hole, which is about a factor of 2 smaller than the increase achieved for the low-density phase. © 2017 Trans Tech Publications, Switzerland.

  • Petrographic and geochemical evidence for multiphase formation of carbonates in the Martian orthopyroxenite Allan Hills 84001

    Moyano-Cambero C.E., Trigo-Rodríguez J.M., Benito M.I., Alonso-Azcárate J., Lee M.R., Mestres N., Martínez-Jiménez M., Martín-Torres F.J., Fraxedas J. Meteoritics and Planetary Science; 52 (6): 1030 - 1047. 2017. 10.1111/maps.12851.

    Force Probe Microscopy and Surface Nanoengineering

    Martian meteorites can provide valuable information about past environmental conditions on Mars. Allan Hills 84001 formed more than 4 Gyr ago, and owing to its age and long exposure to the Martian environment, and this meteorite has features that may record early processes. These features include a highly fractured texture, gases trapped during one or more impact events or during formation of the rock, and spherical Fe-Mg-Ca carbonates. In this study, we have concentrated on providing new insights into the context of these carbonates using a range of techniques to explore whether they record multiple precipitation and shock events. The petrographic features and compositional properties of these carbonates indicate that at least two pulses of Mg- and Fe-rich solutions saturated the rock. Those two generations of carbonates can be distinguished by a very sharp change in compositions, from being rich in Mg and poor in Fe and Mn, to being poor in Mg and rich in Fe and Mn. Between these two generations of carbonate is evidence for fracturing and local corrosion. © 2017 The Authors. Meteoritics & Planetary Science published by Wiley Periodicals, Inc. on behalf of The Meteoritical Society.

  • Photochromism of dihydroazulene-based polymeric thin films

    Torres-Pierna H., Roscini C., Vlasceanu A., Broman S.L., Jevric M., Cacciarini M., Nielsen M.B. Dyes and Pigments; 145: 359 - 364. 2017. 10.1016/j.dyepig.2017.06.015.

    Nanostructured Functional Materials

    We report on the preparation of polymeric thin films doped with six dihydroazulene derivatives whose photochromic properties were previously screened in organic solution studies. Spectroscopic investigations into the photochromic behavior of the polymeric matrices have given important insights on the stability and the photophysical properties of the photoswitches impregnated into polymers. © 2017 Elsevier Ltd

  • Physical characterisation of 3C-SiC(001)/SiO2 interface using XPS

    Li F., Vavasour O., Walker M., Martin D.M., Sharma Y., Russell S., Jennings M., Pérez-Tomás A., Mawby P.A. Materials Science Forum; 897 MSF: 151 - 154. 2017. 10.4028/www.scientific.net/MSF.897.151.

    Oxide Nanophysics

    Normally-on MOSFETs were fabricated on 3C-SiC epilayers (Si face) using high temperature (1300 °C) wet oxidation. XPS analysis found little carbon at the MOS interface yet the channel mobility (60 cm2/V.s) is considerably low. Si suboxides (SiOx, x<2) exist at the wet oxidised 3C-SiC/SiO2 interface, which may act as interface traps and degrade the conduction performance. © 2017 Trans Tech Publications, Switzerland.

  • Physics of Quantum Light Emitters in Disordered Photonic Nanostructures

    García P.D., Lodahl P. Annalen der Physik; 2017. 10.1002/andp.201600351.

    Nanophotonics focuses on the control of light and the interaction with matter by the aid of intricate nanostructures. Typically, a photonic nanostructure is carefully designed for a specific application and any imperfections may reduce its performance, i.e., a thorough investigation of the role of unavoidable fabrication imperfections is essential for any application. However, another approach to nanophotonic applications exists where fabrication disorder is used to induce functionalities by enhancing light-matter interaction. Disorder leads to multiple scattering of light, which is the realm of statistical optics where light propagation requires a statistical description. We review here the recent progress on disordered photonic nanostructures and the potential implications for quantum photonics devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA.

  • Polybenzoxazine-Derived N-doped Carbon as Matrix for Powder-Based Electrocatalysts

    Barwe S., Andronescu C., Masa J., Ventosa E., Klink S., Genç A., Arbiol J., Schuhmann W. ChemSusChem; 10 (12): 2653 - 2659. 2017. 10.1002/cssc.201700593.

    Advanced Electron Nanoscopy

    In addition to catalytic activity, intrinsic stability, tight immobilization on a suitable electrode surface, and sufficient electronic conductivity are fundamental prerequisites for the long-term operation of particle- and especially powder-based electrocatalysts. We present a novel approach to concurrently address these challenges by using the unique properties of polybenzoxazine (pBO) polymers, namely near-zero shrinkage and high residual-char yield even after pyrolysis at high temperatures. Pyrolysis of a nanocubic prussian blue analogue precursor (KmMnx[Co(CN)6]y⋅n H2O) embedded in a bisphenol A and aniline-based pBO led to the formation of a N-doped carbon matrix modified with MnxCoyOz nanocubes. The obtained electrocatalyst exhibits high efficiency toward the oxygen evolution reaction (OER) and more importantly a stable performance for at least 65 h. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

  • Potassium disorder in the defect pyrochlore KSbTeO6: A neutron diffraction study

    Alonso J.A., Mayer S., Falcón H., Turrillas X., Fernández-Díaz M.T. Crystals; 7 (1, 24) 2017. 10.3390/cryst7010024.

    KSbTeO6 defect pyrochlore has been prepared from K2C2O4, Sb2O3, and 15% excess TeO2 by solid-state reaction at 850 °C. Direct methods implemented in the software EXPO2013 allowed establishing the basic structural framework. This was followed by a combined Rietveld refinement from X-ray powder diffraction (XRD) and neutron powder diffraction (NPD) data, which unveiled additional structural features. KSbTeO6 is cubic, a = 10.1226(7) Å, space group Fd3m, Z = 8 and it is made of a mainly covalent framework of corner-sharing (Sb,Te)O6 octahedra, with weakly bonded K+ ions located within large cages. The large K-O distances, 3.05(3)–3.07(3) Å, and quite large anisotropic atomic displacement parameters account for the easiness of K+ exchange for other cations of technological importance. © 2016 by the authors; licensee MDPI, Basel, Switzerland.

  • Preface: Special Issue “27th International Conference on Diamond and Carbon Materials – DCM 2016”

    Haenen K., Garrido J.A. Diamond and Related Materials; 75: A1. 2017. 10.1016/j.diamond.2017.05.006.

    Advanced Electronic Materials and Devices

    [No abstract available]

  • Probing the surface reactivity of nanocrystals by the catalytic degradation of organic dyes: The effect of size, surface chemistry and composition

    Piella J., Merkoçi F., Genç A., Arbiol J., Bastús N.G., Puntes V. Journal of Materials Chemistry A; 5 (23): 11917 - 11929. 2017. 10.1039/c7ta01328k.

    Inorganic Nanoparticles | Advanced Electron Nanoscopy

    We herein present a comprehensive study on how the catalytic performance and reusability of Au nanocrystals (NCs) are affected by systematic variations of crystal size, surface coating and composition. The reductions of different organic dyes (4-nitrophenol, rhodamine B and methylene blue) by borohydride ions were used as model catalytic reactions. The catalytic performance of the Au NCs ranged between 3.6 to 110 nm was found to be dependent on crystal size, indicating that Au surface atoms have a distinct size-dependent reactivity in this reaction. Similarly, the catalytic performance was found to be strongly dependent on the nature of the coating molecule, obtaining lower catalytic activities for molecules strongly bound to the Au surface. Finally, the catalytic performance was found to be dependent on the chemical composition of the NC (Au, Ag, Pt) and the model dye used as a testing system, with the highest degradation rate found for methylene blue, followed by 4-nitrophenol and rhodamine B. We believe that this study provides a better understanding of the catalytic performance of Au NCs upon controlled modifications of the structural and morphological parameters, and a working environment that can be used to facilitate the selection of the optimum NC size, coating molecule and evaluation system for a particular study of interest. © 2017 The Royal Society of Chemistry.

  • Production of biofunctionalized MoS2 flakes with rationally modified lysozyme: A biocompatible 2D hybrid material

    Siepi M., Morales-Narváez E., Domingo N., Monti D.M., Notomista E., Merkoçi A. 2D Materials; 4 (3, 035007) 2017. 10.1088/2053-1583/aa7966.

    Oxide Nanophysics | Nanobioelectronics and Biosensors

    Bioapplications of 2D materials embrace demanding features in terms of environmental impact, toxicity and biocompatibility. Here we report on the use of a rationally modified lysozyme to assist the exfoliation of Mos2 bulk crystals suspended in water through ultrasonic exfoliation. The design of the proposed lysozyme derivative provides this exfoliated 2D-materail with both, hydrophobic groups that interact with the surface of Mos2 and hydrophilic groups exposed to the aqueous medium, which hinders its re-Aggregation. This approach, clarified also by molecular docking studies, leads to a stable material (ζ-potential, 27 ?} 1 mV) with a yield of up to 430 μg ml-1. The bio-hybrid material was characterized in terms of number of layers and optical properties according to different slots separated by diverse centrifugal forces. Furthermore the obtained material was proved to be biocompatible using human normal keratinocytes and human cancer epithelial cells, whereas the method was demonstrated to be applicable to produce other 2D materials such as graphene. This approach is appealing for the advantageous production of high quality Mos2 flakes and their application in biomedicine and biosensing. Moreover, this method can be applied to different starting materials, making the denatured lysozyme a promising bio-Tool for surface functionalization of 2D materials. © 2017 IOP Publishing Ltd.

  • Rapid on-chip apoptosis assay on human carcinoma cells based on annexin-V/quantum dot probes

    Montón H., Medina-Sánchez M., Soler J.A., Chałupniak A., Nogués C., Merkoçi A. Biosensors and Bioelectronics; 94: 408 - 414. 2017. 10.1016/j.bios.2017.03.034.

    Nanobioelectronics and Biosensors

    Despite all the efforts made over years to study the cancer expression and the metastasis event, there is not a clear understanding of its origins and effective treatment. Therefore, more specialized and rapid techniques are required for studying cell behaviour under different drug-based treatments. Here we present a quantum dot signalling-based cell assay carried out in a segmental microfluidic device that allows studying the effect of anti-cancer drugs in cultured cell lines by monitoring phosphatidylserine translocation that occurs in early apoptosis. The developed platform combines the automatic generation of a drug gradient concentration, allowing exposure of cancer cells to different doses, and the immunolabeling of the apoptotic cells using quantum dot reporters. Thereby a complete cell-based assay for efficient drug screening is performed showing a clear correlation between drug dose and amount of cells undergoing apoptosis. © 2017 Elsevier B.V.

  • Safer by design strategies

    Cobaleda-Siles M., Guillamon A.P., Delpivo C., Vázquez-Campos S., Puntes V.F. Journal of Physics: Conference Series; 838 (1, 012016) 2017. 10.1088/1742-6596/838/1/012016.

    Inorganic Nanoparticles

    Throughout the EU funded FP7 project GUIDENano, we are trying to control and monitor the evolution of nano-enable products during their lifecycle. Small alterations of the nanoparticle (NP) state may have critical consequences on the NP behaviour and performance. For this reason it is important to highlight the importance of an extensive and proper characterization to define the NP physico-chemical characteristics under several environmental conditions. Furthermore, this characterization is necessary to ensure that obtained results are reproducible and allow understanding the behaviour of the NP on biological systems. In this paper different strategies reported in the literature regarding the safety-by-design concept are summarized. Several strategies from the synthetic point of view that help us to modulate the main factors which determine the safety of nanomaterials are proposed. © Published under licence by IOP Publishing Ltd.

  • Seeded Growth Synthesis of Au-Fe3O4 Heterostructured Nanocrystals: Rational Design and Mechanistic Insights

    Fantechi E., Roca A.G., Sepúlveda B., Torruella P., Estradé S., Peiró F., Coy E., Jurga S., Bastús N.G., Nogués J., Puntes V. Chemistry of Materials; 29 (9): 4022 - 4035. 2017. 10.1021/acs.chemmater.7b00608.

    Magnetic Nanostructures | Inorganic Nanoparticles

    Multifunctional hybrid nanoparticles comprising two or more entities with different functional properties are gaining ample significance in industry and research. Due to its combination of properties, a particularly appealing example is Au-Fe3O4 composite nanoparticles. Here we present an in-depth study of the synthesis of Au-Fe3O4 heterostructured nanocrystals (HNCs) by thermal decomposition of iron precursors in the presence of preformed 10 nm Au seeds. The role of diverse reaction parameters on the HNCs formation was investigated using two different precursors: iron pentacarbonyl (Fe(CO)5) and iron acetylacetonate (Fe(acac)3). The reaction conditions promoting the heterogeneous nucleation of Fe3O4 onto Au seeds were found to significantly differ depending on the precursor chosen, where Fe(acac)3 is considerably more sensitive to the variation of the parameters than Fe(CO)5 and more subject to homogeneous nucleation processes with the consequent formation of isolated iron oxide nanocrystals (NCs). The role of the surfactants was also crucial in the formation of well-defined and monodisperse HNCs by regulating the access to the Au surface. Similarly, the variations of the [Fe]/[Au] ratio, temperature, and employed solvent were found to act on the mean size and the morphology of the obtained products. Importantly, while the optical properties are rather sensitive to the final morphology, the magnetic ones are rather similar for the different types of obtained HNCs. The surface functionalization of dimer-like HNCs with silica allows their dispersion in aqueous media, opening the path to their use in biomedical applications. © 2017 American Chemical Society.

  • Self-assembled three-dimensional inverted photonic crystals on a photonic chip

    Arpiainen S., Vynck K., Dekker J., Kapulainen M., Khunsin W., Aalto T., Mulot M., Kocher-Oberlehrer G., Zentel R., Torres C.M.S., Cassagne D., Ahopelto J. Physica Status Solidi (A) Applications and Materials Science; 2017. 10.1002/pssa.201700039.

    Three dimensional photonic crystals (PhCs) exhibiting a full photonic band gap have high potential in optical signal processing and detector applications. However, the challenges in the integration of the 3D PhCs into photonic circuits have so far hindered their exploitation in real devices. This article demonstrates the fabrication of 3D PhCs exploiting the capillary directed self-assembly (CDSA) of monodisperse colloidal silica spheres, their inversion to silicon shells, and integration with silicon waveguides. The measured transmission characteristics agree with numerical predictions and provide strong indication of a full photonic band gap in the inverted 3D photonic crystals at wavelengths close to 1.55μm. Silicon inverted photonic crystal self-assembled into a cavity in a waveguide intersection and the corresponding photonic band structure of the crystal, together with the simulated transmission, reflection, and absorption spectra. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  • Selfmix and optomechanics with silicon nitride membrane

    Baldacci L., Pitanti A., Masini L., Arcangeli A., Colangelo F., Navarro-Urrios D., Tredicucci A. Optics InfoBase Conference Papers; Part F43-CLEO_AT 2017 2017. 10.1364/CLEO_AT.2017.JTu5A.21.

    The selfmixer properties of a laser compound cavity are investigated and experimentally exploited to couple the mechanical fluctuations of a silicon nitride membrane to the laser photons and electronical states, producing an active optomechanical system. © 2017 OSA.

  • Size-Dependent Protein-Nanoparticle Interactions in Citrate-Stabilized Gold Nanoparticles: The Emergence of the Protein Corona

    Piella J., Bastús N.G., Puntes V. Bioconjugate chemistry; 28 (1): 88 - 97. 2017. 10.1021/acs.bioconjchem.6b00575.

    Inorganic Nanoparticles

    Surface modifications of highly monodisperse citrate-stabilized gold nanoparticles (AuNPs) with sizes ranging from 3.5 to 150 nm after their exposure to cell culture media supplemented with fetal bovine serum were studied and characterized by the combined use of UV-vis spectroscopy, dynamic light scattering, and zeta potential measurements. In all the tested AuNPs, a dynamic process of protein adsorption was observed, evolving toward the formation of an irreversible hard protein coating known as Protein Corona. Interestingly, the thickness and density of this protein coating were strongly dependent on the particle size, making it possible to identify different transition regimes as the size of the particles increased: (i) NP-protein complexes (or incomplete corona), (ii) the formation of a near-single dense protein corona layer, and (iii) the formation of a multilayer corona. In addition, the different temporal patterns in the evolution of the protein coating came about more quickly for small particles than for the larger ones, further revealing the significant role that size plays in the kinetics of this process. Since the biological identity of the NPs is ultimately determined by the protein corona and different NP-biological interactions take place at different time scales, these results are relevant to biological and toxicological studies.

  • Solution-based synthesis and processing of Sn- and Bi-doped Cu3SbSe4 nanocrystals, nanomaterials and ring-shaped thermoelectric generators

    Liu Y., García G., Ortega S., Cadavid D., Palacios P., Lu J., Ibáñez M., Xi L., De Roo J., López A.M., Martí-Sánchez S., Cabezas I., Mata M.D.L., Luo Z., Dun C., Dobrozhan O., Carroll D.L., Zhang W., Martins J., Kovalenko M.V., Arbiol J., Noriega G., Song J., Wahnón P., Cabot A. Journal of Materials Chemistry A; 5 (6): 2592 - 2602. 2017. 10.1039/c6ta08467b.

    Advanced Electron Nanoscopy

    Copper-based chalcogenides that comprise abundant, low-cost, and environmental friendly elements are excellent materials for a number of energy conversion applications, including photovoltaics, photocatalysis, and thermoelectrics (TE). In such applications, the use of solution-processed nanocrystals (NCs) to produce thin films or bulk nanomaterials has associated several potential advantages, such as high material yield and throughput, and composition control with unmatched spatial resolution and cost. Here we report on the production of Cu3SbSe4 (CASe) NCs with tuned amounts of Sn and Bi dopants. After proper ligand removal, as monitored by nuclear magnetic resonance and infrared spectroscopy, these NCs were used to produce dense CASe bulk nanomaterials for solid state TE energy conversion. By adjusting the amount of extrinsic dopants, dimensionless TE figures of merit (ZT) up to 1.26 at 673 K were reached. Such high ZT values are related to an optimized carrier concentration by Sn doping, a minimized lattice thermal conductivity due to efficient phonon scattering at point defects and grain boundaries, and to an increase of the Seebeck coefficient obtained by a modification of the electronic band structure with Bi doping. Nanomaterials were further employed to fabricate ring-shaped TE generators to be coupled to hot pipes, which provided 20 mV and 1 mW per TE element when exposed to a 160 °C temperature gradient. The simple design and good thermal contact associated with the ring geometry and the potential low cost of the material solution processing may allow the fabrication of TE generators with short payback times. © The Royal Society of Chemistry.

  • Sonochemical synthesis, characterization, and effects of temperature, power ultrasound and reaction time on the morphological properties of two new nanostructured mercury(II) coordination supramolecule compounds

    Hayati P., Rezvani A.R., Morsali A., Molina D.R., Geravand S., Suarez-Garcia S., Villaecija M.A.M., García-Granda S., Mendoza-Meroño R., Retailleau P. Ultrasonics Sonochemistry; 37: 382 - 393. 2017. 10.1016/j.ultsonch.2017.01.021.

    Two new mercury(II) coordination supramolecular compounds (CSCs) (1D and 0D), [Hg(L)(I)2]n (1) and [Hg2(L′)2(SCN)2]·2H2O (2) (L = 2-amino-4-methylpyridine and L′ = 2,6-pyridinedicarboxlic acid), have been synthesized under different experimental conditions. Micrometric crystals (bulk) or nano-sized materials have been obtained depending on using the branch tube method or sonochemical irradiation. All materials have been characterized by field emission scanning electron microscope (FESEM), scanning electron microscopy (SEM), powder X-ray diffraction (PXRD) and FT-IR spectroscopy. Single crystal X-ray analyses on compounds 1 and 2 show that Hg2+ ions are 4-coordinated and 5-coordinated, respectively. Topological analysis shows that the compound 1 and 2 have 2C1, sql net. The thermal stability of compounds 1 and 2 in bulk and nano-size has been studied by thermal gravimetric (TG), differential thermal analyses (DTA) for 1 and differential scanning calorimetry (DSC) for 2, respectively. Also, by changing counter ions were obtained various structures 1 and 2 (1D and 0D, respectively). The role of different parameters like power of ultrasound irradiation, reaction time and temperature on the growth and morphology of the nano-structures are studied. Results suggest that increasing power ultrasound irradiation and temperature together with reducing reaction time and concentration of initial reagents leads to a decrease in particle size. © 2017 The Authors

  • Spin hall effect and weak antilocalization in graphene/transition metal dichalcogenide heterostructures

    Garcia J.H., Cummings A.W., Roche S. Nano Letters; 17 (8): 5078 - 5083. 2017. 10.1021/acs.nanolett.7b02364.

    Theoretical and Computational Nanoscience

    We report on a theoretical study of the spin Hall Effect (SHE) and weak antilocalization (WAL) in graphene/transition metal dichalcogenide (TMDC) heterostructures, computed through efficient real-space quantum transport methods, and using realistic tight-binding models parametrized from ab initio calculations. The graphene/WS2 system is found to maximize spin proximity effects compared to graphene on MoS2, WSe2, or MoSe2 with a crucial role played by disorder, given the disappearance of SHE signals in the presence of strong intervalley scattering. Notably, we found that stronger WAL effects are concomitant with weaker charge-to-spin conversion efficiency. For further experimental studies of graphene/TMDC heterostructures, our findings provide guidelines for reaching the upper limit of spin current formation and for fully harvesting the potential of two-dimensional materials for spintronic applications. © 2017 American Chemical Society.

  • Spin precession in anisotropic media

    Raes B., Cummings A.W., Bonell F., Costache M.V., Sierra J.F., Roche S., Valenzuela S.O. Physical Review B; 95 (8, 085403) 2017. 10.1103/PhysRevB.95.085403.

    Theoretical and Computational Nanoscience | Physics and Engineering of Nanodevices

    We generalize the diffusive model for spin injection and detection in nonlocal spin structures to account for spin precession under an applied magnetic field in an anisotropic medium, for which the spin lifetime is not unique and depends on the spin orientation. We demonstrate that the spin precession (Hanle) line shape is strongly dependent on the degree of anisotropy and on the orientation of the magnetic field. In particular, we show that the anisotropy of the spin lifetime can be extracted from the measured spin signal, after dephasing in an oblique magnetic field, by using an analytical formula with a single fitting parameter. Alternatively, after identifying the fingerprints associated with the anisotropy, we propose a simple scaling of the Hanle line shapes at specific magnetic field orientations that results in a universal curve only in the isotropic case. The deviation from the universal curve can be used as a complementary means of quantifying the anisotropy by direct comparison with the solution of our generalized model. Finally, we applied our model to graphene devices and find that the spin relaxation for graphene on silicon oxide is isotropic within our experimental resolution. © 2017 American Physical Society.

  • Spray drying for making covalent chemistry: Postsynthetic modification of metal-organic frameworks

    Garzón-Tovar L., Rodríguez-Hermida S., Imaz I., Maspoch D. Journal of the American Chemical Society; 139 (2): 897 - 903. 2017. 10.1021/jacs.6b11240.

    Supramolecular NanoChemistry and Materials

    Covalent postsynthetic modification (PSM) of metal-organic frameworks (MOFs) has attracted much attention due to the possibility of tailoring the properties of these porous materials. Schiff-base condensation betwecn an amine and an aldehyde is one of the most common reactions in the PSM of MOFs. Here, we report the use of the spray drying technique to perform this class of organic reactions, either betwecn discrete organic molecules or on the pore surfaces of MOFs, in a very fast (1-2 s) and continuous way. Using spray drying, we show the PSM of two MOFs, the amine-terminated UiO-66-NH2 and the aldehyde-terminated ZIF-90, achieving conversion efficiencies up to 20 and 42%, respectively. Moreover, we demonstrate that it can also be used to postsynthetically cross-link the aldehyde groups of ZIF-90 using a diamine molecule with a conversion efficiency of 70%. © 2017 American Chemical Society.

  • Structural, optical, and photoelectrochemical properties of nanosphere-like CdXZn1-XS synthesized by electrochemical route

    Dhaygude H.D., Shinde S.K., Dubal D.P., Velhal N.B., Kim D.-Y., Fulari V.J. Ionics; 23 (1): 223 - 231. 2017. 10.1007/s11581-016-1797-8.

    Novel Energy-Oriented Materials

    Here, we present the effect of different Zn contents on the structural, morphological, and optical properties of CdXZn1-XS thin films deposited by electrodeposition method on stainless steel and indium-doped tin oxide (ITO) glass substrates. Electrosynthesized CdXZn1-XS thin films are characterized by using X-ray diffraction (XRD), UV-Vis spectrophotometer, field emission scanning electron microscope (FE-SEM), and surface wettability analysis. XRD pattern reveals that the CdXZn1-XS thin films are polycrystalline in nature with hexagonal crystal structure. FE-SEM micrograph displays that these CdXZn1-XS thin films exhibit the different sizes of sphere-like nanostructures by varying the X value. The optical absorption study indicates that drastic variation in band gap energy of CdXZn1-XS thin films. In advance photovoltaic measurements, CdXZn1-XS thin films are to be studied by forming the photoelectrochemical (PEC) cell having CdXZn1-XS/0.5 M (Na2SO3)/C configuration. The efficiency values of CdXZn1-XS are found to be 0.2, 0.35, 0.32, 0.25, and 0.23 % respectively at X content. © 2016, Springer-Verlag Berlin Heidelberg.

  • Surface-Guided Core-Shell ZnSe@ZnTe Nanowires as Radial p-n Heterojunctions with Photovoltaic Behavior

    Oksenberg E., Martí-Sánchez S., Popovitz-Biro R., Arbiol J., Joselevich E. ACS Nano; 11 (6): 6155 - 6166. 2017. 10.1021/acsnano.7b02199.

    Advanced Electron Nanoscopy

    The organization of nanowires on surfaces remains a major obstacle toward their large-scale integration into functional devices. Surface-material interactions have been used, with different materials and substrates, to guide horizontal nanowires during their growth into well-organized assemblies, but the only guided nanowire heterostructures reported so far are axial and not radial. Here, we demonstrate the guided growth of horizontal core-shell nanowires, specifically of ZnSe@ZnTe, with control over their crystal phase and crystallographic orientations. We exploit the directional control of the guided growth for the parallel production of multiple radial p-n heterojunctions and probe their optoelectronic properties. The devices exhibit a rectifying behavior with photovoltaic characteristics upon illumination. Guided nanowire heterostructures enable the bottom-up assembly of complex semiconductor structures with controlled electronic and optoelectronic properties. © 2017 American Chemical Society.

  • Symmetry forbidden morphologies and domain boundaries in nanoscale graphene islands

    Parreiras S.O., Gastaldo M., Moreno C., Martins M.D., Garcia-Lekue A., Ceballos G., Paniago R., Mugarza A. 2D Materials; 4 (2, 025104) 2017. 10.1088/2053-1583/aa70fa.

    Atomic Manipulation and Spectroscopy

    The synthesis of graphene nanoislands with tailored quantum properties requires an atomic control of the morphology and crystal structure. As one reduces their size down to the nanometer scale, domain boundary and edge energetics, as well as nucleation and growth mechanisms impose different stability and kinetic landscape from that at the microscale. This offers the possibility to synthesize structures that are exclusive to the nanoscale, but also calls for fundamental growth studies in order to control them. By employing high-resolution scanning tunneling microscopy we elucidate the atomic stacking configurations, domain boundaries, and edge structure of graphene nanoislands grown on Ni(1 1 1) by CVD and post-annealed at different temperatures. We find a non-conventional multistep mechanism that separates the thermal regimes for growth, edge reconstruction, and final stacking configuration, leading to nanoisland morphologies that are incompatible with their stacking symmetry. Whole islands shift their stacking configuration during cooling down, and others present continuous transitions at the edges. A statistical analysis of the domain structures obtained at different annealing temperatures reveals how polycrystalline, ill-defined structures heal into shape-selected islands of a single predominant stacking. The high crystallinity and the control on morphology and edge structure makes these graphene nanoislands ideal for their application in optoelectronics and spintronics. © 2017 IOP Publishing Ltd.

  • Synthesis and characterization of a new nano lead(II) 0-D coordination supramolecular compound: A precursor to produce pure phase nano-sized lead(II) oxide

    Fard M.J.S., Hayati P., Naraghi H.S., Tabeie S.A. Ultrasonics Sonochemistry; 39: 129 - 136. 2017. 10.1016/j.ultsonch.2017.04.023.

    Nano-structure of a new 0D Pb(II) coordination supramolecular compound, [Pb4(8-Quin)6](ClO4)2(1), L = 8-HQuin = 8-hydroxyquinolin ligand has been synthesized by use of a sonochemical process and characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FTIR) and elemental analyses. The structure of compound 1 was determined by single-crystal X-ray diffraction. The single crystal X-ray data of compound 1 implies that the Pb+2 ions are five coordinated. Each lead atom is coordinated to nitrogen and oxygen atoms of 8-hydroxyquinolin ligand. Topological analysis shows that the compound 1 is 1,2,3,4,4M12-1net. Nanoparticles of lead(II) oxide have been prepared by calcination of lead(II) coordination polymer at 500 °C that were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRPD) and IR spectroscopy. © 2017 Elsevier B.V.

  • Synthesis and optical characterization of Er-doped bismuth titanate nanoparticles grown by sol–gel hydrothermal method

    Fuentes S., Muñoz P., Llanos J., Vega M., Martin I.R., Chavez-Angel E. Ceramics International; 43 (4): 3623 - 3630. 2017. 10.1016/j.ceramint.2016.11.200.

    The Er3+-doped bismuth titanate (Bi4Ti3O12, BIT) nanoparticles were synthesized by a combined sol–gel and hydrothermal method under a partial oxygen pressure of 30 bar. The composition and morphology were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman scattering. They showed pure and homogeneous spherical BIT nanoparticles with a size below the 30 nm. The incorporation of Er ions showed a strong decrease in the lattice parameters, as well as averaged particle size. The photoluminescence up-conversion (excitation wavelength =1480 nm) showed an enhancement of the infrared emission (980 nm) as Er concentration increased, achieving a maximum for 6% mol, while photoluminescence spectra (excitation wavelength =473 nm) showed a strong green emission (529 and 553 nm) with a maximum at 4% mol. © 2016 Elsevier Ltd and Techna Group S.r.l.

  • Synthesis of Polydopamine-Like Nanocapsules via Removal of a Sacrificial Mesoporous Silica Template with Water

    Nador F., Guisasola E., Baeza A., Villaecija M.A.M., Vallet-Regí M., Ruiz-Molina D. Chemistry - A European Journal; 23 (12): 2753 - 2758. 2017. 10.1002/chem.201604631.

    Nanostructured Functional Materials

    Hollow polymeric polydopamine (PDA) micro-/nanocapsules have been obtained through a very simple, mild, and straightforward method that involves coating of silica mesoporous nanoparticles through an ammonia-triggered polymerization of PDA and the posterior removal of the sacrificial template simply by dispersion in water, without the need of any harsh chemical reagent, either in the presence or absence of active principles, from doxorubicin to iron oxide nanoparticles. To demonstrate the potential of the nanocapsules obtained with this new approach, they have been successfully used as nanocarriers for drug delivery. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

  • Systematic study of the impact of MOF densification into tablets on textural and mechanical properties

    Dhainaut J., Avci-Camur C., Troyano J., Legrand A., Canivet J., Imaz I., Maspoch D., Reinsch H., Farrusseng D. CrystEngComm; 19 (29): 4211 - 4218. 2017. 10.1039/c7ce00338b.

    Supramolecular NanoChemistry and Materials

    Four different metal-organic framework powders (UiO-66, UiO-66-NH2, UiO-67, and HKUST-1) were shaped into tablets. The effect of the applied pressure on porous properties, mechanical resistance and tablet bulk density is reported. We observe a linear relationship between densification and tensile strength for all four studied MOFs, with the slope being MOF-dependent. We also report conditions for improving significantly the volumetric uptake. Finally, we evaluated our tablets' stability over time in the presence of moisture. © 2017 The Royal Society of Chemistry.

  • Tailoring magnetic insulator proximity effects in graphene: First-principles calculations

    Hallal A., Ibrahim F., Yang H., Roche S., Chshiev M. 2D Materials; 4 (2, 025074) 2017. 10.1088/2053-1583/aa6663.

    Theoretical and Computational Nanoscience

    We report a systematic first-principles investigation of the influence of different magnetic insulators on the magnetic proximity effect induced in graphene. Four different magnetic insulators are considered: two ferromagnetic europium chalcogenides namely EuO and EuS and two ferrimagnetic insulators yttrium iron garnet (YIG) and cobalt ferrite (CFO). The obtained exchange-splitting in graphene varies from tens to hundreds of meV depending on substrates. We find an electron doping to graphene induced by YIG and europium chalcogenides substrates, that shift the Fermi level above the Dirac cone up to 0.78 eV and 1.3 eV respectively, whereas hole doping shifts the Fermi level down below the Dirac cone about 0.5 eV in graphene/CFO. Furthermore, we study the variation of the extracted exchange and tight-binding parameters as a function of the EuO and EuS thicknesses. We show that those parameters are robust to thickness variation such that a single monolayer of magnetic insulator can induce a strong magnetic proximity effect on graphene. Those findings pave the way towards possible engineering of graphene spin-gating by proximity effect especially in view of recent experimental advancements. © 2017 IOP Publishing Ltd.

  • Thermal conductivity of epitaxially grown InP: experiment and simulation

    Jaramillo-Fernandez J., Chavez-Angel E., Sanatinia R., Kataria H., Anand S., Lourdudoss S., Sotomayor-Torres C.M. CrystEngComm; 19 (14): 1879 - 1887. 2017. 10.1039/c6ce02642g.

    Phononic and Photonic Nanostructures

    The integration of III-V optoelectronic devices on silicon is confronted with the challenge of heat dissipation for reliable and stable operation. A thorough understanding and characterization of thermal transport is paramount for improved designs of, for example, viable III-V light sources on silicon. In this work, the thermal conductivity of heteroepitaxial laterally overgrown InP layers on silicon is experimentally investigated using microRaman thermometry. By examining InP mesa-like structures grown from trenches defined by a SiO2 mask, we found that the thermal conductivity decreases by about one third, compared to the bulk thermal conductivity of InP, with decreasing width from 400 to 250 nm. The high thermal conductivity of InP grown from 400 nm trenches was attributed to the lower defect density as the InP microcrystal becomes thicker. In this case, the thermal transport is dominated by phonon-phonon interactions as in a low defect-density monocrystalline bulk material, whereas for thinner InP layers grown from narrower trenches, the heat transfer is dominated by phonon scattering at the extended defects and InP/SiO2 interface. In addition to the nominally undoped sample, sulfur-doped (1 × 1018 cm−3) InP grown on Si was also studied. For the narrower doped InP microcrystals, the thermal conductivity decreased by a factor of two compared to the bulk value. Sources of errors in the thermal conductivity measurements are discussed. The experimental temperature rise was successfully simulated by the heat diffusion equation using the FEM. © The Royal Society of Chemistry.

  • Toward integrated detection and graphene-based removal of contaminants in a lab-on-a-chip platform

    Chałupniak A., Merkoçi A. Nano Research; 10 (7): 2296 - 2310. 2017. 10.1007/s12274-016-1420-3.

    Nanobioelectronics and Biosensors

    A novel, miniaturized microfluidic platform was developed for the simultaneous detection and removal of polybrominated diphenyl ethers (PBDEs). The platform consists of a polydimethylsiloxane (PDMS) microfluidic chip for an immunoreaction step, a PDMS chip with an integrated screen-printed electrode (SPCE) for detection, and a PDMS-reduced graphene oxide (rGO) chip for physical adsorption and subsequent removal of PBDE residues. The detection was based on competitive immunoassay-linked binding between PBDE and PBDE modified with horseradish peroxidase (HRP-PBDE) followed by the monitoring of enzymatic oxidation of o-aminophenol (o-AP) using square wave anodic stripping voltammetry (SW-ASV). PBDE was detected with good sensitivity and a limit of detection similar to that obtained with a commercial colorimetric test (0.018 ppb), but with the advantage of using lower reagent volumes and a reduced analysis time. The use of microfluidic chips also provides improved linearity and a better reproducibility in comparison to those obtained with batch-based measurements using screen-printed electrodes. In order to design a detection system suitable for toxic compounds such as PBDEs, a reduced graphene oxide–PDMS composite was developed and optimized to obtain increased adsorption (based on both the hydrophobicity and π–π stacking between rGO and PBDE molecules) compared to those of non-modified PDMS. To the best of our knowledge, this is the first demonstration of electrochemical detection of flame retardants and a novel application of the rGO-PDMS composite in a biosensing system. This system can be easily applied to detect any analyte using the appropriate immunoassay and it supports operation in complex matrices such as seawater. [Figure not available: see fulltext.]. © 2016, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

  • Tuning the electronic properties of monolayer and bilayer transition metal dichalcogenide compounds under direct out-of-plane compression

    García Á.M., Corro E.D., Kalbac M., Frank O. Physical Chemistry Chemical Physics; 19 (20): 13333 - 13340. 2017. 10.1039/c7cp00012j.

    The band-gap modulation of atomically thin semiconductor transition metal dichalcogenides (MX2; M = Mo or W, X = S or Se) under direct out-of-plane compression is systematically studied by means of the density functional theory (DFT) formalism including spin-orbit coupling (SOC) and dispersion correction (D3). The out-of-plane compared with other regimes stress regime significantly reduces the pressure threshold at which the semimetal state is achieved (2.7-3.1 and 1.9-3.2 GPa for mono- and bilayer systems, respectively). Structural, electronic and bonding properties are investigated for a better understanding of the electronic transitions achieved with compression. A notable relationship with the formal ionic radius (M4+ and X2-) is obtained. On one hand, the monolayer systems with the smallest transition metal radius (Mo4+ < W4+) reach the semimetal state at lower stress, on the other hand, for bilayer specimens the transition to semimetal is observed earlier for compounds with the smallest chalcogenide radius (S2- < Se2-). Moreover, the appearance of non-covalent interaction (NCI) domains in the semimetal state confirms that the out-of-plane compression promotes the interaction between sulfur atoms in the single layered systems and reduces the interlayer space in bilayer configurations. Our predictions, supported by experimental evidences in the case of monolayered MoS2, demonstrate new alternative methods for tuning the electronic properties of transition metal dichalcogenides under direct out-of-plane compression. © 2017 the Owner Societies.

  • Ultrahigh energy density supercapacitors through a double hybrid strategy

    Dubal D.P., Nagar B., Suarez-Guevara J., Tonti D., Enciso E., Palomino P., Gomez-Romero P. Materials Today Energy; 5: 58 - 65. 2017. 10.1016/j.mtener.2017.05.001.

    Novel Energy-Oriented Materials

    Herein, we are presenting all-solid-state symmetric supercapacitors (ASSSCs) with an innovative double hybrid strategy, where a hybrid material based on reduced graphene oxide (rGO) anchored with phoshotungstic acid, rGO-H3PW12O40) is combined with hybrid electrolyte (hydroquinone-doped gel electrolyte). Initially, a hybrid electrode is fabricated by decorating H3PW12O40 nanodots onto the surface rGO (rGO-PW12). Next, a symmetric cell based on rGO-PW12 electrodes was assembled with PVA-H2SO4 polymer gel-electrolyte. Interestingly, rGO-PW12 symmetric cell revealed a substantial enhancement in the cell performance as compared to parent rGO systems. It featured a widened potential range of 1.6 V, thereby providing 1.05 mWh/cm3 energy density. The electrochemical performance of rGO-PW12 cell was further advanced by introducing redox-active (hydroquinone) species in to the PVA-H2SO4 gel-electrolyte. Indeed, the performance of rGO-PW12 cell was surprisingly improved with an ultra-high energy density of 2.38 mWh/cm3 (more than two-fold). © 2017 Elsevier Ltd

  • Ultrathin High Surface Area Nickel Boride (NixB) Nanosheets as Highly Efficient Electrocatalyst for Oxygen Evolution

    Masa J., Sinev I., Mistry H., Ventosa E., de la Mata M., Arbiol J., Muhler M., Roldan Cuenya B., Schuhmann W. Advanced Energy Materials; 2017. 10.1002/aenm.201700381.

    Advanced Electron Nanoscopy

    The overriding obstacle to mass production of hydrogen from water as the premium fuel for powering our planet is the frustratingly slow kinetics of the oxygen evolution reaction (OER). Additionally, inadequate understanding of the key barriers of the OER is a hindrance to insightful design of advanced OER catalysts. This study presents ultrathin amorphous high-surface area nickel boride (NixB) nanosheets as a low-cost, very efficient and stable catalyst for the OER for electrochemical water splitting. The catalyst affords 10 mA cm-2 at 0.38 V overpotential during OER in 1.0 m KOH, reducing to only 0.28 V at 20 mA cm-2 when supported on nickel foam, which ranks it among the best reported nonprecious catalysts for oxygen evolution. Operando X-ray absorption fine-structure spectroscopy measurements reveal prevalence of NiOOH, as well as Ni-B under OER conditions, owing to a Ni-B core at nickel oxyhydroxide shell (Ni-B at NiOxH) structure, and increase in disorder of the NiOxH layer, thus revealing important insight into the transient states of the catalyst during oxygen evolution. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  • Ultrathin Mesoporous RuCo2O4 Nanoflakes: An Advanced Electrode for High-Performance Asymmetric Supercapacitors

    Dubal D.P., Chodankar N.R., Holze R., Kim D.-H., Gomez-Romero P. ChemSusChem; 10 (8): 1771 - 1782. 2017. 10.1002/cssc.201700001.

    Novel Energy-Oriented Materials

    A new ruthenium cobalt oxide (RuCo2O4) with a unique marigold-like nanostructure and excellent performance as an advanced electrode material has been successfully prepared by a simple electrodeposition (potentiodynamic mode) method. The RuCo2O4 marigolds consist of numerous clusters of ultrathin mesoporous nanoflakes, leaving a large interspace between them to provide numerous electrochemically active sites. Strikingly, this unique marigold-like nanostructure provided excellent electrochemical performance in terms of high energy-storage capacitance (1469 F g−1 at 6 A g−1) with excellent rate proficiency and long-lasting operating cycling stability (ca. 91.3 % capacitance retention after 3000 cycles), confirming that the mesoporous nanoflakes participate in the ultrafast electrochemical reactions. Furthermore, an asymmetric supercapacitor was assembled using RuCo2O4 (positive electrode) and activated carbon (negative electrode) with aqueous KOH electrolyte. The asymmetric design allowed an upgraded potential range of 1.4 V, which further provided a good energy density of 32.6 Wh kg−1 (1.1 mWh cm−3). More importantly, the cell delivered an energy density of 12.4 Wh kg−1 even at a maximum power density of 3.2 kW kg−1, which is noticeably superior to carbon-based symmetric systems. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

  • Unveiling the nucleation & coarsening mechanisms of solution-derived self-Assembled epitaxial Ce0.9Gd0.1O2-yNanostructures

    Queralto A., De La Mata M., Arbiol J., Hühne R., Obradors X., Puig T. Crystal Growth and Design; 17 (2): 504 - 516. 2017. 10.1021/acs.cgd.6b01358.

    Advanced Electron Nanoscopy

    Self-Assembling approaches based on chemical solution deposition (CSD) are ideal methods for the cost-effective production of epitaxial nanostructures with high throughput. Therefore, an in-depth investigation of the nucleation and coarsening processes involved in the self-Assembly of nanostructures is mandatory to achieve a good control over nanostructure shape, dimensions, and orientation. Heteroepitaxial Ce0.9Gd0.1O2-y (CGO) is an ideal model system to unveil the underlying nanostructure development mechanisms in addition to their promising properties for catalysis, gas sensors, and ionic conductivity. Rapid thermal annealing furnaces have been used to study separately the thermodynamic and kinetic nucleation and coarsening mechanisms of self-Assembled CGO isotropic and anisotropic nanostructures based on strain-engineering and surface energies control. Different CGO nanoislands are obtained: isotropic (001)CGO nanodots are grown on (001)-oriented Y2O3:ZrO2(YSZ) and LaAlO3 (Lao) substrates, whereas (011)Lao substrates promote the growth of elongated (011)CGO nanowires. HRTEM and RHEED analyses are used to study the early stages of nucleation, as well as the shape and interfacial structure of CGO nanostructures. A systematic study with the heating ramp, annealing temperature and time, and strain in combination with thermally activated theoretical models provides information on the nucleation behavior, nucleation barriers, and atomic diffusion coefficients along in-plane and out-of-plane island orientations. Highly anisotropic atomic diffusion constants have been shown to be at the origin of the high aspect ratios of some of the nanostructures. Overall, our study provides a general method for the evaluation of nucleation and coarsening of multiple CSD-derived oxide nanostructures and understanding the shape development by combining thermodynamic and kinetic approaches. ©2016 American Chemical Society.

  • V2O5 encapsulated MWCNTs in 2D surface architecture: Complete solid-state bendable highly stabilized energy efficient supercapacitor device

    Pandit B., Dubal D.P., Gómez-Romero P., Kale B.B., Sankapal B.R. Scientific Reports; 7 ( 43430) 2017. 10.1038/srep43430.

    Novel Energy-Oriented Materials

    A simple and scalable approach has been reported for 2O5 encapsulation over interconnected multi-walled carbon nanotubes (MWCNTs) network using chemical bath deposition method. Chemically synthesized 2O5/MWCNTs electrode exhibited excellent charge-discharge capability with extraordinary cycling retention of 93% over 4000 cycles in liquid-electrolyte. Electrochemical investigations have been performed to evaluate the origin of capacitive behavior from dual contribution of surface-controlled and diffusion-controlled charge components. Furthermore, a complete flexible solid-state, flexible symmetric supercapacitor (FSS-SSC) device was assembled with 2O5/MWCNTs electrodes which yield remarkable values of specific power and energy densities along with enhanced cyclic stability over liquid configuration. As a practical demonstration, the constructed device was used to lit the 'VNIT' acronym assembled using 21 LED's. © The Author(s) 2017.

  • Voltage-Induced Coercivity Reduction in Nanoporous Alloy Films: A Boost toward Energy-Efficient Magnetic Actuation

    Quintana A., Zhang J., Isarain-Chávez E., Menéndez E., Cuadrado R., Robles R., Baró M.D., Guerrero M., Pané S., Nelson B.J., Müller C.M., Ordejón P., Nogués J., Pellicer E., Sort J. Advanced Functional Materials; 27 (32, 1701904) 2017. 10.1002/adfm.201701904.

    Theory and Simulation | Magnetic Nanostructures

    Magnetic data storage and magnetically actuated devices are conventionally controlled by magnetic fields generated using electric currents. This involves significant power dissipation by Joule heating effect. To optimize energy efficiency, manipulation of magnetic information with lower magnetic fields (i.e., lower electric currents) is desirable. This can be accomplished by reducing the coercivity of the actuated material. Here, a drastic reduction of coercivity is observed at room temperature in thick (≈600 nm), nanoporous, electrodeposited Cu–Ni films by simply subjecting them to the action of an electric field. The effect is due to voltage-induced changes in the magnetic anisotropy. The large surface-area-to-volume ratio and the ultranarrow pore walls of the system allow the whole film, and not only the topmost surface, to effectively contribute to the observed magnetoelectric effect. This waives the stringent “ultrathin-film requirement” from previous studies, where small voltage-driven coercivity variations were reported. This observation expands the already wide range of applications of nanoporous materials (hitherto in areas like energy storage or catalysis) and it opens new paradigms in the fields of spintronics, computation, and magnetic actuation in general. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim