ICN2 Publications


  • A High Conductivity 1D π–d Conjugated Metal–Organic Framework with Efficient Polysulfide Trapping-Diffusion-Catalysis in Lithium–Sulfur Batteries

    Yang D., Liang Z., Tang P., Zhang C., Tang M., Li Q., Biendicho J.J., Li J., Heggen M., Dunin-Borkowski R.E., Xu M., Llorca J., Arbiol J., Morante J.R., Chou S.-L., Cabot A. Advanced Materials; 34 (10, 2108835) 2022. 10.1002/adma.202108835. IF: 30.849

    Advanced Electron Nanoscopy

    The shuttling behavior and sluggish conversion kinetics of the intermediate lithium polysulfides (LiPS) represent the main obstructions to the practical application of lithium–sulfur batteries (LSBs). Herein, a 1D π–d conjugated metal–organic framework (MOF), Ni-MOF-1D, is presented as an efficient sulfur host to overcome these limitations. Experimental results and density functional theory calculations demonstrate that Ni-MOF-1D is characterized by a remarkable binding strength for trapping soluble LiPS species. Ni-MOF-1D also acts as an effective catalyst for S reduction during the discharge process and Li2S oxidation during the charging process. In addition, the delocalization of electrons in the π–d system of Ni-MOF-1D provides a superior electrical conductivity to improve electron transfer. Thus, cathodes based on Ni-MOF-1D enable LSBs with excellent performance, for example, impressive cycling stability with over 82% capacity retention over 1000 cycles at 3 C, superior rate performance of 575 mAh g−1 at 8 C, and a high areal capacity of 6.63 mAh cm−2 under raised sulfur loading of 6.7 mg cm−2. The strategies and advantages here demonstrated can be extended to a broader range of π–d conjugated MOFs materials, which the authors believe have a high potential as sulfur hosts in LSBs. © 2022 Wiley-VCH GmbH

  • A Novel Ratiometric Fluorescent Approach for the Modulation of the Dynamic Range of Lateral Flow Immunoassays

    Sena-Torralba A., Torné-Morató H., Parolo C., Ranjbar S., Farahmand Nejad M.A., Álvarez-Diduk R., Idili A., Hormozi-Nezhad M.R., Merkoçi A. Advanced Materials Technologies; 2022. 10.1002/admt.202101450. IF: 7.848

    Nanobioelectronics and Biosensors

    The majority of lateral flow assays (LFAs) use single-color optical labels to provide a qualitative naked-eye detection, however this detection method displays two important limitations. First, the use of a single-color label makes the LFA prone to results misinterpretation. Second, it does not allow the precise modulation of the sensitivity and dynamic range of the test. To overcome these limitations, a ratiometric approach is developed. In particular, using anti-HIgG functionalized red-fluorescent quantum dots on the conjugate pad (as target dependent labels) and blue-fluorescent nanoparticles fixed on the test line (as target independent reporters), it is possible to generate a wide color palette (blue, purple, pink, red) on the test line. It is believed that this strategy will facilitate the development of LFAs by easily adjusting their analytical properties to the needs required by the specific application. © 2022 The Authors. Advanced Materials Technologies published by Wiley-VCH GmbH

  • A novel π-d conjugated cobalt tetraaza[14]annulene based atomically dispersed electrocatalyst for efficient CO2 reduction

    Liang Z., Zhang T., Cao P., Yoshida T., Tang W., Wang X., Zuo Y., Tang P., Heggen M., Dunin-Borkowski R.E., Morante J.R., Cabot A., Yamashita M., Arbiol J. Chemical Engineering Journal; 442 (136129) 2022. 10.1016/j.cej.2022.136129. IF: 13.273

    Advanced Electron Nanoscopy

    Tetraaza[14]annulenes (TAA) are synthetic macrocycles which are analogue to porphyrins. However, there are almost no reports about the synthesis of polymers based on TAA and neither on their use as electrocatalysts. The study of new catalysts to promote an efficient electrochemical conversion of carbon dioxide to valuable chemicals is a promising approach to relieve the pressure of carbon emissions and realize the carbon cycle. Herein, we first report the synthesis of a novel tetraaza[14]annulene (TAA) based organic polymeric metal complex (PMC) by a non-template method. This PMC is used as ligand to construct a π-d conjugated cobalt coordination polymer (Poly-TAA-Co) with CoN4 structure which is supported on multi-wall carbon nanotubes (CNTs) to work as an atomically dispersed efficient electrocatalyst for the CO2 reduction reaction (CO2RR). The resulting catalyst (Poly-TAA-Co-CNT) exhibits excellent performance, with a 90% CO faradaic efficiency, a low overpotential (390 mV) and good stability in 0.5 M KHCO3 aqueous solution. Density functional theory calculations confirmed that the cobalt tetra[14]annulene is an excellent active site for electrocatalytic CO2RR. This work not only inspires the design of novel TAA based macromolecules, but also paves the way to the development and application of new molecular-based catalysts for electrocatalytic CO2RR. © 2022 The Author(s)

  • A plug, print & play inkjet printing and impedance-based biosensing technology operating through a smartphone for clinical diagnostics

    Rosati G., Urban M., Zhao L., Yang Q., de Carvalho Castro e Silva C., Bonaldo S., Parolo C., Nguyen E.P., Ortega G., Fornasiero P., Paccagnella A., Merkoçi A. Biosensors and Bioelectronics; 196 (113737) 2022. 10.1016/j.bios.2021.113737. IF: 10.618

    Nanobioelectronics and Biosensors

    Simplicity is one of the key feature for the spread of any successful technological product. Here, a method for rapid and low-cost fabrication of electrochemical biosensors is presented. This “plug, print & play” method involves inkjet-printing even in an office-like environment, without the need of highly specialized expertise or equipment, guaranteeing an ultra-fast idea to (scaled) prototype production time. The printed biosensors can be connected to a smartphone through its audio input for their impedance readout, demonstrating the validity of the system for point-of-care biosensing. Proper electrodes layout guarantees high sensitivity and is validated by finite element simulations. The introduction of a passivation method (wax printing) allowed to complete the devices fabrication process, increasing their sensitivity. Indeed, the wax allowed reducing the interference related to the parasitic currents flowing through the permeable coating of the employed substrates, which was used for the chemical sintering, thus avoiding the common thermal treatment after printing. As a case study, we used the devices to develop an electrochemical aptamer-based sensor for the rapid detection of neutrophil gelatinase-associated lipocalin (NGAL) in urine – a clinically important marker of acute kidney injury. The aptasensor platform is capable of detecting clinically relevant concentrations of NGAL with a simple and rapid smartphone readout. The developed technology may be extended in the future to continuous monitoring, taking advantage of its flexibility to integrate it in tubes, or to other diagnostic applications where cost/efficiency and rapidity of the research, development and implementation of point of care devices is a must. © 2021

  • Activating the lattice oxygen oxidation mechanism in amorphous molybdenum cobalt oxide nanosheets for water oxidation

    Wang X., Xing C., Liang Z., Guardia P., Han X., Zuo Y., Llorca J., Arbiol J., Li J., Cabot A. Journal of Materials Chemistry A; 10 (7): 3659 - 3666. 2022. 10.1039/d1ta09657e. IF: 12.732

    Advanced Electron Nanoscopy

    The cost-effective deployment of several key energy technologies, such as water electrolysis, CO2 electroreduction and metal-air batteries, relies on the design and engineering of cost-effective catalysts able to accelerate the sluggish kinetics of the oxygen evolution reaction (OER). Herein, we detail the synthesis, processing and performance of a cobalt oxide-based OER electrocatalyst with optimized composition, atomic arrangement and nano/microstructure. We demonstrate that doping the cobalt oxide with a higher electronegativity element such as molybdenum promotes the participation of lattice oxygen in the OER. Besides, the processing of the catalyst at moderate temperatures results in an amorphous material with extended compositional and atomic arrangement versatility. Additionally, the catalyst, which is produced through an ion etching assisted strategy using ZIF-67 as a template, displays a highly porous structure in the form of amorphous ultrathin MoCoxOy nanosheets that maximize interaction with the media and facilitate the transport of ions through the electrolyte. After optimizing the molybdenum concentration and structural parameters, the best MoCoxOy catalysts exhibited a low overpotential of 282 mV at 10 mA cm-2 with a reduced Tafel slope of 60.6 mV dec-1, and excellent stability with more than 60 h operation without significant activity decay. © 2022 The Royal Society of Chemistry.

  • Amorphizing noble metal chalcogenide catalysts at the single-layer limit towards hydrogen production

    He Y., Liu L., Zhu C., Guo S., Golani P., Koo B., Tang P., Zhao Z., Xu M., Zhu C., Yu P., Zhou X., Gao C., Wang X., Shi Z., Zheng L., Yang J., Shin B., Arbiol J., Duan H., Du Y., Heggen M., Dunin-Borkowski R.E., Guo W., Wang Q.J., Zhang Z., Liu Z. Nature Catalysis; 5 (3): 212 - 221. 2022. 10.1038/s41929-022-00753-y. IF: 41.813

    Advanced Electron Nanoscopy

    Rational design of noble metal catalysts with the potential to leverage efficiency is vital for industrial applications. Such an ultimate atom-utilization efficiency can be achieved when all noble metal atoms exclusively contribute to catalysis. Here, we demonstrate the fabrication of a wafer-size amorphous PtSex film on a SiO2 substate via a low-temperature amorphization strategy, which offers single-atom-layer Pt catalysts with high atom-utilization efficiency (~26 wt%). This amorphous PtSex (1.2 < x < 1.3) behaves as a fully activated surface, accessible to catalytic reactions, and features a nearly 100% current density relative to a pure Pt surface and reliable production of sustained high-flux hydrogen over a 2 inch wafer as a proof-of-concept. Furthermore, an electrolyser is demonstrated to generate a high current density of 1,000 mA cm−2. Such an amorphization strategy is potentially extendable to other noble metals, including the Pd, Ir, Os, Rh and Ru elements, demonstrating the universality of single-atom-layer catalysts. [Figure not available: see fulltext.] © 2022, The Author(s), under exclusive licence to Springer Nature Limited.

  • An innovative autonomous robotic system for on-site detection of heavy metal pollution plumes in surface water

    De Vito-Francesco E., Farinelli A., Yang Q., Nagar B., Álvarez R., Merkoçi A., Knutz T., Haider A., Stach W., Ziegenbalg F., Allabashi R. Environmental Monitoring and Assessment; 194 (2, 122) 2022. 10.1007/s10661-021-09738-z. IF: 2.513

    Nanobioelectronics and Biosensors

    Smart monitoring has been studied and developed in recent years to create faster, cheaper, and more user-friendly on-site methods. The present study describes an innovative technology for investigative monitoring of heavy metal pollution (Cu and Pb) in surface water. It is composed of an autonomous surface vehicle capable of semiautonomous driving and equipped with a microfluidic device for detection of heavy metals. Detection is based on the method of square wave anodic stripping voltammetry using carbon-based screen-printed electrodes (SPEs). The focus of this work was to validate the ability of the integrated system to perform on-site detection of heavy metal pollution plumes in river catchments. This scenario was simulated in laboratory experiments. The main performance characteristics of the system, which was evaluated based on ISO 15839 were measurement bias (Pb 75%, Cu 65%), reproducibility (in terms of relative standard deviation: Pb 11–18%, Cu 6–10%) and the limit of detection (4 µg/L for Pb and 7 µg/L for Cu). The lowest detectable change (LDC), which is an important performance characteristic for this application, was estimated to be 4–5 µg/L for Pb and 6–7 µg/L for Cu. The life span of an SPE averaged 39 measurements per day, which is considered sufficient for intended monitoring campaigns. This work demonstrated the suitability of the integrated system for on-site detection of Pb and Cu emissions from large and medium urban areas discharging into small water bodies. © 2022, The Author(s).

  • Antibacterial Films Based on MOF Composites that Release Iodine Passively or Upon Triggering by Near-Infrared Light

    Han X., Boix G., Balcerzak M., Moriones O.H., Cano-Sarabia M., Cortés P., Bastús N., Puntes V., Llagostera M., Imaz I., Maspoch D. Advanced Functional Materials; 2022. 10.1002/adfm.202112902. IF: 18.808

    Supramolecular NanoChemistry and Materials | Inorganic Nanoparticles

    Multidrug-resistant bacteria have become a global health problem for which new prophylactic strategies are now needed, including surface-coatings for hospital spaces and medical equipment. This work reports the preparation and functional validation of a metal-organic framework (MOF) based composite for the triggered controlled release of iodine, an antimicrobial element that does not generate resistance. It comprises beads of the iodophilic MOF UiO-66 containing encapsulated gold nanorods (AuNRs) coated with a silica shell. Irradiation of the AuNRs with near-infrared light (NIR) provokes a photothermal effect and the resultant heat actively liberates the iodine. After validating the performance of this composite, it is integrated into a polymer for the development of antibacterial films. This work assesses the adsorption of iodine into these composite films, as well as its passive long-term release and active light-triggered. Finally, this work validates the antibacterial activity of the composite films in vitro against gram-positive and gram-negative bacteria. The findings will surely inform the development of new prophylactic treatments. © 2022 Wiley-VCH GmbH

  • Atomically Sharp Lateral Superlattice Heterojunctions Built-In Nitrogen-Doped Nanoporous Graphene

    Tenorio M., Moreno C., Febrer P., Castro-Esteban J., Ordejón P., Peña D., Pruneda M., Mugarza A. Advanced Materials; 2022. 10.1002/adma.202110099. IF: 30.849

    Theory and Simulation | Atomic Manipulation and Spectroscopy

    Nanometer scale lateral heterostructures with atomically sharp band discontinuities can be conceived as the 2D analogues of vertical Van der Waals heterostructures, where pristine properties of each component coexist with interfacial phenomena that result in a variety of exotic quantum phenomena. However, despite considerable advances in the fabrication of lateral heterostructures, controlling their covalent interfaces and band discontinuities with atomic precision, scaling down components and producing periodic, lattice-coherent superlattices still represent major challenges. Here, a synthetic strategy to fabricate nanometer scale, coherent lateral superlattice heterojunctions with atomically sharp band discontinuity is reported. By merging interdigitated arrays of different types of graphene nanoribbons by means of a novel on-surface reaction, superlattices of 1D, and chemically heterogeneous nanoporous junctions are obtained. The latter host subnanometer quantum dipoles and tunneling in-gap states, altogether expected to promote interfacial phenomena such as interribbon excitons or selective photocatalysis. © 2022 The Authors. Advanced Materials published by Wiley-VCH GmbH.

  • Clip-off Chemistry: Synthesis by Programmed Disassembly of Reticular Materials**

    Yang Y., Broto-Ribas A., Ortín-Rubio B., Imaz I., Gándara F., Carné-Sánchez A., Guillerm V., Jurado S., Busqué F., Juanhuix J., Maspoch D. Angewandte Chemie - International Edition; 61 (4, e202111228) 2022. 10.1002/anie.202111228. IF: 15.336

    Supramolecular NanoChemistry and Materials

    Bond breaking is an essential process in chemical transformations and the ability of researchers to strategically dictate which bonds in a given system will be broken translates to greater synthetic control. Here, we report extending the concept of selective bond breaking to reticular materials in a new synthetic approach that we call Clip-off Chemistry. We show that bond-breaking in these structures can be controlled at the molecular level; is periodic, quantitative, and selective; is effective in reactions performed in either solid or liquid phases; and can occur in a single-crystal-to-single-crystal fashion involving the entire bulk precursor sample. We validate Clip-off Chemistry by synthesizing two topologically distinct 3D metal-organic frameworks (MOFs) from two reported 3D MOFs, and a metal-organic macrocycle from metal-organic polyhedra (MOP). Clip-off Chemistry opens the door to the programmed disassembly of reticular materials and thus to the design and synthesis of new molecules and materials. © 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH

  • Coherent Integration of Organic Gel Polymer Electrolyte and Ambipolar Polyoxometalate Hybrid Nanocomposite Electrode in a Compact High-Performance Supercapacitor

    Zhu J.-J., Martinez-Soria L., Gomez-Romero P. Nanomaterials; 12 (3, 514) 2022. 10.3390/nano12030514. IF: 5.076

    Novel Energy-Oriented Materials

    We report a gel polymer electrolyte (GPE) supercapacitor concept with improved pathways for ion transport, thanks to a facile creation of a coherent continuous distribution of the electrolyte throughout the electrode. Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) was chosen as the polymer framework for organic electrolytes. A permeating distribution of the GPE into the electrodes, acting both as integrated electrolyte and binder, as well as thin separator, promotes ion diffusion and increases the active electrode–electrolyte interface, which leads to improvements both in capacitance and rate capability. An activation process induced during the first charge–discharge cycles was detected, after which, the charge transfer resistance and Warburg impedance decrease. We found that a GPE thickness of 12 μm led to optimal capacitance and rate capability. A novel hybrid nanocomposite material, formed by the tetraethylammonium salt of the 1 nm-sized phosphomolybdate cluster and activated carbon (AC/TEAPMo12), was shown to improve its capacitive performance with this gel electrolyte arrangement. Due to the homogeneous dispersion of PMo12 clusters, its energy storage process is non-diffusion-controlled. In the symmetric capacitors, the hybrid nanocomposite material can perform redox reactions in both the positive and the negative electrodes in an ambipolar mode. The volumetric capacitance of a symmetric supercapacitor made with the hybrid electrodes increased by 40% compared to a cell with parent AC electrodes. Due to the synergy between permeating GPE and the hybrid electrodes, the GPE hybrid symmetric capacitor delivers three times more energy density at higher power densities and equivalent cycle stability compared with conventional AC symmetric capacitors. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

  • Coloration in Supraparticles Assembled from Polyhedral Metal-Organic Framework Particles

    Wang J., Liu Y., Bleyer G., Goerlitzer E.S.A., Englisch S., Przybilla T., Mbah C.F., Engel M., Spiecker E., Imaz I., Maspoch D., Vogel N. Angewandte Chemie - International Edition; 61 (16, e202117455) 2022. 10.1002/anie.202117455. IF: 15.336

    Supramolecular NanoChemistry and Materials

    Supraparticles are spherical colloidal crystals prepared by confined self-assembly processes. A particularly appealing property of these microscale structures is the structural color arising from interference of light with their building blocks. Here, we assemble supraparticles with high structural order that exhibit coloration from uniform, polyhedral metal–organic framework (MOF) particles. We analyse the structural coloration as a function of the size of these anisotropic building blocks and their internal structure. We attribute the angle-dependent coloration of the MOF supraparticles to the presence of ordered, onion-like layers at the outermost regions. Surprisingly, even though different shapes of the MOF particles have different propensities to form these onion layers, all supraparticle dispersions show well-visible macroscopic coloration, indicating that local ordering is sufficient to generate interference effects. © 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.

  • Competition between Ta-Ta and Te-Te bonding leading to the commensurate charge density wave in TaTe4

    Guster B., Pruneda M., Ordejón P., Canadell E. Physical Review B; 105 (6, 064107) 2022. 10.1103/PhysRevB.105.064107. IF: 4.036

    Theory and Simulation

    The origin of the charge density wave in TaTe4 is discussed on the basis of a first-principles density functional theory analysis of the Fermi surface, electron-hole response function, phonon band structure of the average structure, and structural optimization of the modulated phase. Analysis of the band structure and Fermi surface of the average structure clearly proves that despite the presence of TaTe4 chains in the crystal structure, TaTe4 is in fact a 3D material as far as the electronic structure near the Fermi level is concerned. A Fermi surface nesting mechanism is dismissed as the origin of the 2a×2a×3c structural modulation. The optimized 2a×2a×3c structure, which is found to be the more stable modulation in agreement with the experimental observations, can be obtained directly from a soft-phonon mode computed for the undistorted structure. Our results suggest that the driving force for the distortion is the maximization of Ta-Ta metal-metal bonding subject to inducing the minimum bonding decrease in the Te sublattice. © 2022 American Physical Society.

  • Conductive properties of triphenylene MOFs and COFs

    Contreras-Pereda N., Pané S., Puigmartí-Luis J., Ruiz-Molina D. Coordination Chemistry Reviews; 460 (214459) 2022. 10.1016/j.ccr.2022.214459. IF: 22.315

    Nanostructured Functional Materials

    Triphenylene (TP) based materials have experienced a great expansion in the latest years. TP molecules have interesting optoelectronic properties, arising from the aromatic core, which have been exploited in functional two-dimensional (2D) Metal-Organic Frameworks (MOFs) and Covalent Organic Frameworks (COFs) aside other organic polymers. In this review we summarize synthetic approaches of TP-based 2D MOFs and COFs emphasizing on the resulting morphology, crystalline domains and orientation, proven to have great impact on the properties and performance of these materials in functional devices. Specifically, we report a detailed description on the different TP-based 2D structures detailing the influence of the chemical and crystalline structure on the electronic properties, specially the in-plane and out-of-plane contribution to the electrical conductivity. Finally, we give also attention and present several examples of functional devices made out with these electronic materials with great impact in the literature as well as in future technological applications. © 2022 The Authors

  • Controlled oxygen doping in highly dispersed Ni-loaded g-C3N4 nanotubes for efficient photocatalytic H2O2 production

    Du R., Xiao K., Li B., Han X., Zhang C., Wang X., Zuo Y., Guardia P., Li J., Chen J., Arbiol J., Cabot A. Chemical Engineering Journal; 441 (135999) 2022. 10.1016/j.cej.2022.135999. IF: 13.273

    Advanced Electron Nanoscopy

    Hydrogen peroxide (H2O2) is both a key component in several industrial processes and a promising liquid fuel. The production of H2O2 by solar photocatalysis is a suitable strategy to convert and store solar energy into chemical energy. Here we report an oxygen-doped tubular g-C3N4 with uniformly dispersed nickel nanoparticles for efficient photocatalytic H2O2 generation. The hollow structure of the tubular g-C3N4 provides a large surface with a high density of reactive sites and efficient visible light absorption during the photocatalytic reaction. The oxygen doping and Ni loading enable a fast separation of photogenerated charge carriers and a high selectivity toward the two-electron process during the oxygen reduction reaction (ORR). The optimized composition, Ni4%/O0.2tCN, displays an H2O2 production rate of 2464 μmol g−1·h−1, which is eightfold higher than that of bulk g-C3N4 under visible light irradiation (λ > 420 nm), and achieves an apparent quantum yield (AQY) of 28.2% at 380 nm and 14.9% at 420 nm. © 2022 Elsevier B.V.

  • Critical Role of Phosphorus in Hollow Structures Cobalt-Based Phosphides as Bifunctional Catalysts for Water Splitting

    Zhang W., Han N., Luo J., Han X., Feng S., Guo W., Xie S., Zhou Z., Subramanian P., Wan K., Arbiol J., Zhang C., Liu S., Xu M., Zhang X., Fransaer J. Small; 18 (4, 2103561) 2022. 10.1002/smll.202103561. IF: 13.281

    Advanced Electron Nanoscopy

    Cobalt phosphides electrocatalysts have great potential for water splitting, but the unclear active sides hinder the further development of cobalt phosphides. Wherein, three different cobalt phosphides with the same hollow structure morphology (CoP-HS, CoP2-HS, CoP3-HS) based on the same sacrificial template of ZIF-67 are prepared. Surprisingly, these cobalt phosphides exhibit similar OER performances but quite different HER performances. The identical OER performance of these CoPx-HS in alkaline solution is attributed to the similar surface reconstruction to CoOOH. CoP-HS exhibits the best catalytic activity for HER among these CoPx-HS in both acidic and alkaline media, originating from the adjusted electronic density of phosphorus to affect absorption–desorption process on H. Moreover, the calculated ΔGH* based on P-sites of CoP-HS follows a quite similar trend with the normalized overpotential and Tafel slope, indicating the important role of P-sites for the HER process. Moreover, CoP-HS displays good performance (cell voltage of 1.67 V at a current density of 50 mA cm−2) and high stability in 1 M KOH. For the first time, this work detailly presents the critical role of phosphorus in cobalt-based phosphides for water splitting, which provides the guidance for future investigations on transition metal phosphides from material design to mechanism understanding. © 2021 Wiley-VCH GmbH

  • Defect Engineering in Solution-Processed Polycrystalline SnSe Leads to High Thermoelectric Performance

    Liu Y., Calcabrini M., Yu Y., Lee S., Chang C., David J., Ghosh T., Spadaro M.C., Xie C., Cojocaru-Mirédin O., Arbiol J., Ibáñez M. ACS Nano; 16 (1): 78 - 88. 2022. 10.1021/acsnano.1c06720. IF: 15.881

    Advanced Electron Nanoscopy

    SnSe has emerged as one of the most promising materials for thermoelectric energy conversion due to its extraordinary performance in its single-crystal form and its low-cost constituent elements. However, to achieve an economic impact, the polycrystalline counterpart needs to replicate the performance of the single crystal. Herein, we optimize the thermoelectric performance of polycrystalline SnSe produced by consolidating solution-processed and surface-engineered SnSe particles. In particular, the SnSe particles are coated with CdSe molecular complexes that crystallize during the sintering process, forming CdSe nanoparticles. The presence of CdSe nanoparticles inhibits SnSe grain growth during the consolidation step due to Zener pinning, yielding a material with a high density of grain boundaries. Moreover, the resulting SnSe-CdSe nanocomposites present a large number of defects at different length scales, which significantly reduce the thermal conductivity. The produced SnSe-CdSe nanocomposites exhibit thermoelectric figures of merit up to 2.2 at 786 K, which is among the highest reported for solution-processed SnSe. © 2022 American Chemical Society. All rights reserved.

  • Direct Observation of the Chemical Transformations in BiVO4 Photoanodes upon Prolonged Light-Aging Treatments

    Arcas R., Cardenas-Morcoso D., Spadaro M.C., García-Tecedor M., Mesa C.A., Arbiol J., Fabregat-Santiago F., Giménez S., Mas-Marzá E. Solar RRL; 2022. 10.1002/solr.202200132. IF: 8.582

    Advanced Electron Nanoscopy

    Exposing BiVO4 photoanodes to light-aging treatments is known to produce a significant photocurrent enhancement. Until now, the interpretation given to this phenomenon is associated to the formation of oxygen vacancies and little is reported about chemical changes in the material. Herein, the chemical segregation of Bi species toward the surface upon light-aging treatment is demonstrated, which takes place with the concomitant formation of intra-bandgap states associated to the oxygen vacancies. It is further demonstrated that these intra-bandgap states are photoactive and generate photocurrent under infrared excitation. These results highlight the importance of understanding light-induced effects while employing multinary metal oxide photoelectrodes. © 2022 The Authors. Solar RRL published by Wiley-VCH GmbH.

  • Doubling the mobility of InAs/InGaAs selective area grown nanowires

    Beznasyuk D.V., Martí-Sánchez S., Kang J.-H., Tanta R., Rajpalke M., Stankevič T., Christensen A.W., Spadaro M.C., Bergamaschini R., Maka N.N., Petersen C.E.N., Carrad D.J., Jespersen T.S., Arbiol J., Krogstrup P. Physical Review Materials; 6 (3, 034602) 2022. 10.1103/PhysRevMaterials.6.034602. IF: 3.989

    Advanced Electron Nanoscopy

    Selective area growth (SAG) of nanowires and networks promise a route toward scalable electronics, photonics, and quantum devices based on III-V semiconductor materials. The potential of high-mobility SAG nanowires however is not yet fully realised, since interfacial roughness, misfit dislocations at the nanowire/substrate interface and nonuniform composition due to material intermixing all scatter electrons. Here, we explore SAG of highly lattice-mismatched InAs nanowires on insulating GaAs(001) substrates and address these key challenges. Atomically smooth nanowire/substrate interfaces are achieved with the use of atomic hydrogen (a-H) as an alternative to conventional thermal annealing for the native oxide removal. The problem of high lattice mismatch is addressed through an InxGa1-xAs buffer layer introduced between the InAs transport channel and the GaAs substrate. The Ga-In material intermixing observed in both the buffer layer and the channel is inhibited via careful tuning of the growth temperature. Performing scanning transmission electron microscopy and x-ray diffraction analysis along with low-temperature transport measurements we show that optimized In-rich buffer layers promote high-quality InAs transport channels with the field-effect electron mobility over 10 000 cm2 V-1 s-1. This is twice as high as for nonoptimized samples and among the highest reported for InAs selective area grown nanostructures. © 2022 American Physical Society.

  • Dramatic Drop in Cell Resistance through Induced Dipoles and Bipolar Electrochemistry

    Fuentes-Rodríguez L., Abad L., Pujades E., Gómez-Romero P., Tonti D., Casa-Pastor N. Journal of the Electrochemical Society; 169 (1, 016508) 2022. 10.1149/1945-7111/ac492d. IF: 4.316

    Novel Energy-Oriented Materials

    The use of slurries of conducting particles has been considered a way to extend the electrode area in some energy storage electrochemical cells. When suspensions of conducting particles are used in electrolytes a decreased impedance is observed, even for concentrations much lower than the theoretical percolation limits. Indeed, it is known that polarization occurs when a conducting material is immersed in an electrolyte in presence of electric fields, and bipolar electrochemistry processes may occur. This work demonstrates the dramatic drop in resistance for electrochemical cells with just a few macroscopic conducting pieces immersed in the electrolyte, in the absence of any electrical contact, through bipolar induction. Furthermore, mediation of soluble redox species between adjacent induced poles of opposite charge results in an additional mechanism for charge transfer, contributing further to the decrease in impedance. Relevant parameters like size, geometry, and spatial occupation of inducible pieces within the electric field, are relevant. Remarkably, the effects observed can explain some empirical observations previously reported for carbon suspensions and slurries. Thus, no electronic percolation requiring particle contact, nor ordering, are needed to explain the good performance associated to lowered impedance These results suggest new engineering designs for electrochemical cells with enhanced currents. © 2022 The Electrochemical Society ("ECS"). Published on behalf of ECS by IOP Publishing Limited.

  • Dynamic electric-field-induced magnetic effects in cobalt oxide thin films: Towards magneto-ionic synapses

    Martins S., De Rojas J., Tan Z., Cialone M., Lopeandia A., Herrero-Martin J., Costa-Kramer J.L., Menendez E., Sort J. Nanoscale; 14 (3): 842 - 852. 2022. 10.1039/d1nr06210g. IF: 7.790

    Thermal Properties of Nanoscale Materials

    Voltage control of magnetism via electric-field-driven ion migration (magneto-ionics) has generated intense interest due to its potential to greatly reduce heat dissipation in a wide range of information technology devices, such as magnetic memories, spintronic systems or artificial neural networks. Among other effects, oxygen ion migration in transition-metal-oxide thin films can lead to the generation or full suppression of controlled amounts of ferromagnetism ('ON-OFF' magnetic transitions) in a non-volatile and fully reversible manner. However, oxygen magneto-ionic rates at room temperature are generally considered too slow for industrial applications. Here, we demonstrate that sub-second ON-OFF transitions in electrolyte-gated paramagnetic cobalt oxide films can be achieved by drastically reducing the film thickness from >200 nm down to 5 nm. Remarkably, cumulative magneto-ionic effects can be generated by applying voltage pulses at frequencies as high as 100 Hz. Neuromorphic-like dynamic effects occur at these frequencies, including potentiation (cumulative magnetization increase), depression (i.e., partial recovery of magnetization with time), threshold activation, and spike time-dependent magnetic plasticity (learning and forgetting capabilities), mimicking many of the biological synapse functions. The systems under investigation show features that could be useful for the design of artificial neural networks whose magnetic properties would be governed with voltage. This journal is © The Royal Society of Chemistry.

  • Effects of exsolution on the stability and morphology of Ni nanoparticles on BZY thin films

    Jennings D., Ricote S., Santiso J., Caicedo J., Reimanis I. Acta Materialia; 228 (117752) 2022. 10.1016/j.actamat.2022.117752. IF: 8.203

    Nanomaterials Growth Unit

    Yttria doped barium zirconate (BZY) is of interest for use as a catalyst support material, supporting exsolved Ni nanoparticles. Exsolution has been hypothesized to impart catalytic nanoparticles with exceptional resistance to particle coarsening, a known degradation mechanism in catalysts. However, the mechanisms and kinetics of Ni nanoparticle coarsening in BZY are unknown. This work analyzes the kinetics of the coarsening of exsolved Ni nanoparticles on epitaxial BZY thin films at three temperatures (600, 700, and 800 ∘C) over a time span of 150 h. It is demonstrated that Ni coarsening transitions from an Ostwald ripening process to particle migration and coalescence after Ni particles reach a critical size. The coarsening behavior of BZY/Ni is shown to be dependent on the BZY surface orientation, with Ni particles on (111) oriented thin films coarsening the least. The preferred orientation relationships between Ni and BZY on (100), (110), and (111) oriented films are determined. Additionally, the morphology of Ni particles produced through exsolution and thin film dewetting are compared, showing that the socketing behavior and interfacial energy are independent of the Ni particle preparation method. © 2022

  • Elastic Plasmonic-Enhanced Fabry–Pérot Cavities with Ultrasensitive Stretching Tunability

    Güell-Grau P., Pi F., Villa R., Eskilson O., Aili D., Nogués J., Sepúlveda B., Alvarez M. Advanced Materials; 34 (7, 2106731) 2022. 10.1002/adma.202106731. IF: 30.849

    Magnetic Nanostructures

    The emerging stretchable photonics field faces challenges, like the robust integration of optical elements into elastic matrices or the generation of large optomechanical effects. Here, the first stretchable plasmonic-enhanced and wrinkled Fabry–Pérot (FP) cavities are demonstrated, which are composed of self-embedded arrays of Au nanostructures at controlled depths into elastomer films. The novel self-embedding process is triggered by the Au nanostructures’ catalytic activity, which locally increases the polymer curing rate, thereby inducing a mechanical stress that simultaneously pulls the Au nanostructures into the polymer and forms a wrinkled skin layer. This geometry yields unprecedented optomechanical effects produced by the coupling of the broad plasmonic modes of the Au nanostructures and the FP modes, which are modulated by the wrinkled optical cavity. As a result, film stretching induces drastic changes in both the spectral position and intensity of the plasmonic-enhanced FP resonances due to the simultaneous cavity thickness reduction and cavity wrinkle flattening, thus increasing the cavity finesse. These optomechanical effects are exploited to demonstrate new strain-sensing approaches, achieving a strain detection limit of 0.006%, i.e., 16-fold lower than current optical strain-detection schemes. © 2022 Wiley-VCH GmbH

  • Electrically Tunable Nonequilibrium Optical Response of Graphene

    Pogna E.A.A., Tomadin A., Balci O., Soavi G., Paradisanos I., Guizzardi M., Pedrinazzi P., Mignuzzi S., Tielrooij K.-J., Polini M., Ferrari A.C., Cerullo G. ACS Nano; 16 (3): 3613 - 3624. 2022. 10.1021/acsnano.1c04937. IF: 15.881

    Ultrafast Dynamics in Nanoscale Systems

    The ability to tune the optical response of a material via electrostatic gating is crucial for optoelectronic applications, such as electro-optic modulators, saturable absorbers, optical limiters, photodetectors, and transparent electrodes. The band structure of single layer graphene (SLG), with zero-gap, linearly dispersive conduction and valence bands, enables an easy control of the Fermi energy, EF, and of the threshold for interband optical absorption. Here, we report the tunability of the SLG nonequilibrium optical response in the near-infrared (1000-1700 nm/0.729-1.240 eV), exploring a range of EFfrom -650 to 250 meV by ionic liquid gating. As EFincreases from the Dirac point to the threshold for Pauli blocking of interband absorption, we observe a slow-down of the photobleaching relaxation dynamics, which we attribute to the quenching of optical phonon emission from photoexcited charge carriers. For EFexceeding the Pauli blocking threshold, photobleaching eventually turns into photoinduced absorption, because the hot electrons' excitation increases the SLG absorption. The ability to control both recovery time and sign of the nonequilibrium optical response by electrostatic gating makes SLG ideal for tunable saturable absorbers with controlled dynamics. © 2022 American Chemical Society. All rights reserved.

  • Electrochemical reforming of ethanol with acetate Co-Production on nickel cobalt selenide nanoparticles

    Li J., Wang X., Xing C., Li L., Mu S., Han X., He R., Liang Z., Martinez P., Yi Y., Wu Q., Pan H., Arbiol J., Cui C., Zhang Y., Cabot A. Chemical Engineering Journal; 440 (135817) 2022. 10.1016/j.cej.2022.135817. IF: 13.273

    Advanced Electron Nanoscopy

    The energy efficiency of water electrolysis is limited by the sluggish reaction kinetics of the anodic oxygen evolution reaction (OER). To overcome this limitation, OER can be replaced by a less demanding oxidation reaction, which in the ideal scenario could be even used to generate additional valuable chemicals. Herein, we focus on the electrochemical reforming of ethanol in alkaline media to generate hydrogen at a Pt cathode and acetate as a co-product at a Ni1-xCoxSe2 anode. We first detail the solution synthesis of a series of Ni1-xCoxSe2 electrocatalysts. By adjusting the Ni/Co ratio, the electrocatalytic activity and selectivity for the production of acetate from ethanol are optimized. Best performances are obtained at low substitutions of Ni by Co in the cubic NiSe2 phase. Density function theory reveals that the Co substitution can effectively enhance the ethanol adsorption and decrease the energy barrier for its first step dehydrogenation during its conversion to acetate. However, we experimentally observe that too large amounts of Co decrease the ethanol-to-acetate Faradaic efficiency from values above 90% to just 50 %. At the optimized composition, the Ni0.75Co0.25Se2 electrode delivers a stable chronoamperometry current density of up to 45 mA cm−2, corresponding to 1.2 A g−1, in a 1 M KOH + 1 M ethanol solution, with a high ethanol-to-acetate Faradaic efficiency of 82.2% at a relatively low potential, 1.50 V vs. RHE, and with an acetate production rate of 0.34 mmol cm−2 h−1. © 2022 Elsevier B.V.

  • Emerging properties of non-crystalline phases of graphene and boron nitride based materials

    Antidormi A., Colombo L., Roche S. Nano Materials Science; 4 (1): 10 - 17. 2022. 10.1016/j.nanoms.2021.03.003. IF: 0.000

    Theoretical and Computational Nanoscience

    We review recent developments on the synthesis and properties of two-dimensional materials which, although being mainly of an sp2 bonding character, exhibit highly disordered, non-uniform and structurally random morphologies. The emergence of such class of amorphous materials, including amorphous graphene and boron nitride, have shown superior properties compared to their crystalline counterparts when used as interfacial films. In this paper we discuss their structural, vibrational and electronic properties and present a perspective of their use for electronic applications. © 2021 Chongqing University

  • Enhanced Polysulfide Conversion with Highly Conductive and Electrocatalytic Iodine-Doped Bismuth Selenide Nanosheets in Lithium–Sulfur Batteries

    Li M., Yang D., Biendicho J.J., Han X., Zhang C., Liu K., Diao J., Li J., Wang J., Heggen M., Dunin-Borkowski R.E., Wang J., Henkelman G., Morante J.R., Arbiol J., Chou S.-L., Cabot A. Advanced Functional Materials; 2022. 10.1002/adfm.202200529. IF: 18.808

    Advanced Electron Nanoscopy

    The shuttling behavior and sluggish conversion kinetics of intermediate lithium polysulfides (LiPS) represent the main obstacles to the practical application of lithium–sulfur batteries (LSBs). Herein, an innovative sulfur host is proposed, based on an iodine-doped bismuth selenide (I-Bi2Se3), able to solve these limitations by immobilizing the LiPS and catalytically activating the redox conversion at the cathode. The synthesis of I-Bi2Se3 nanosheets is detailed here and their morphology, crystal structure, and composition are thoroughly. Density-functional theory and experimental tools are used to demonstrate that I-Bi2Se3 nanosheets are characterized by a proper composition and micro- and nano-structure to facilitate Li+ diffusion and fast electron transportation, and to provide numerous surface sites with strong LiPS adsorbability and extraordinary catalytic activity. Overall, I-Bi2Se3/S electrodes exhibit outstanding initial capacities up to 1500 mAh g−1 at 0.1 C and cycling stability over 1000 cycles, with an average capacity decay rate of only 0.012% per cycle at 1 C. Besides, at a sulfur loading of 5.2 mg cm−2, a high areal capacity of 5.70 mAh cm−2 at 0.1 C is obtained with an electrolyte/sulfur ratio of 12 µL mg−1. This work demonstrated that doping is an effective way to optimize the metal selenide catalysts in LSBs. © 2022 Wiley-VCH GmbH

  • Extended-SWIR Photodetection in All-Group IV Core/Shell Nanowires

    Luo L., Assali S., Atalla M.R.M., Koelling S., Attiaoui A., Daligou G., Martí S., Arbiol J., Moutanabbir O. ACS Photonics; 9 (3): 914 - 921. 2022. 10.1021/acsphotonics.1c01728. IF: 7.529

    Advanced Electron Nanoscopy

    Group IV Ge1-xSnx semiconductors hold the premise of enabling broadband silicon-integrated infrared optoelectronics due to their tunable band gap energy and directness. Herein, we exploit these attributes along with the enhanced lattice strain relaxation in Ge/Ge0.92Sn0.08 core/shell nanowire heterostructures to implement highly responsive room-temperature short-wave infrared nanoscale photodetectors. Atomic-level studies confirm the uniform shell composition and its higher crystallinity with respect to thin films counterparts. The demonstrated Ge/Ge0.92Sn0.08 p-type field-effect nanowire transistors exhibit superior optoelectronic properties achieving simultaneously relatively high mobility, high ON/OFF ratio, and high responsivity, in addition to a broadband absorption in the short-wave infrared range. Indeed, the reduced band gap of the Ge0.92Sn0.08 shell yields an extended cutoff wavelength of 2.1 μm, with a room-temperature responsivity reaching 2.7 A/W at 1550 nm. These results highlight the potential of Ge/Ge1-xSnx core/shell nanowires as silicon-compatible building blocks for nanoscale-integrated infrared photonics. © 2022 American Chemical Society.

  • Full orbital decomposition of Yu-Shiba-Rusinov states based on first principles

    Saunderson T.G., Annett J.F., Csire G., Gradhand M. Physical Review B; 105 (1, 014424) 2022. 10.1103/PhysRevB.105.014424. IF: 4.036

    We have implemented the Bogoliubov-de Gennes equation in a screened Korringa-Kohn-Rostoker method for solving, self-consistently, the superconducting state for three-dimensional (3D) crystals including substitutional impurities. In this paper we extend this theoretical framework to allow for collinear magnetism and apply it to fcc Pb with 3D magnetic impurities. In the presence of magnetic impurities, there is a pair-breaking effect that results in in-gap Yu-Shiba-Rusinov (YSR) states which we decompose into contributions from the individual orbital character. We determine the spatial extent of these impurity states, showing how the different orbital character affects the details of the YSR states within the superconducting gap. Our work highlights the importance of a first-principles-based description which captures the quantitative details, making direct comparisons with experimental findings possible. © 2022 American Physical Society.

  • Full-bandwidth electrophysiology of seizures and epileptiform activity enabled by flexible graphene microtransistor depth neural probes

    Bonaccini Calia A., Masvidal-Codina E., Smith T.M., Schäfer N., Rathore D., Rodríguez-Lucas E., Illa X., De la Cruz J.M., Del Corro E., Prats-Alfonso E., Viana D., Bousquet J., Hébert C., Martínez-Aguilar J., Sperling J.R., Drummond M., Halder A., Dodd A., Barr K., Savage S., Fornell J., Sort J., Guger C., Villa R., Kostarelos K., Wykes R.C., Guimerà-Brunet A., Garrido J.A. Nature Nanotechnology; 17 (3): 301 - 309. 2022. 10.1038/s41565-021-01041-9. IF: 39.213

    Nanomedicine | Advanced Electronic Materials and Devices

    Mapping the entire frequency bandwidth of brain electrophysiological signals is of paramount importance for understanding physiological and pathological states. The ability to record simultaneously DC-shifts, infraslow oscillations (<0.1 Hz), typical local field potentials (0.1–80 Hz) and higher frequencies (80–600 Hz) using the same recording site would particularly benefit preclinical epilepsy research and could provide clinical biomarkers for improved seizure onset zone delineation. However, commonly used metal microelectrode technology suffers from instabilities that hamper the high fidelity of DC-coupled recordings, which are needed to access signals of very low frequency. In this study we used flexible graphene depth neural probes (gDNPs), consisting of a linear array of graphene microtransistors, to concurrently record DC-shifts and high-frequency neuronal activity in awake rodents. We show here that gDNPs can reliably record and map with high spatial resolution seizures, pre-ictal DC-shifts and seizure-associated spreading depolarizations together with higher frequencies through the cortical laminae to the hippocampus in a mouse model of chemically induced seizures. Moreover, we demonstrate the functionality of chronically implanted devices over 10 weeks by recording with high fidelity spontaneous spike-wave discharges and associated infraslow oscillations in a rat model of absence epilepsy. Altogether, our work highlights the suitability of this technology for in vivo electrophysiology research, and in particular epilepsy research, by allowing stable and chronic DC-coupled recordings. © 2021, The Author(s), under exclusive licence to Springer Nature Limited.

  • Functionalization of filled radioactive multi-walled carbon nanocapsules by arylation reaction forin vivodelivery of radio-therapy

    Gajewska A., Wang J.T., Klippstein R., Martincic M., Pach E., Feldman R., Saccavini J.-C., Tobias G., Ballesteros B., Al-Jamal K.T., Da Ros T. Journal of Materials Chemistry B; 10 (1): 47 - 56. 2022. 10.1039/d1tb02195h. IF: 6.331

    Electron Microscopy Unit

    Functionalized multi-walled carbon nanotubes (MWCNTs) containing radioactive salts are proposed as a potential system for radioactivity delivery. MWCNTs are loaded with isotopically enriched 152-samarium chloride (152SmCl3), the ends of the MWCNTs are sealed by high temperature treatment, and the encapsulated152Sm is neutron activated to radioactive153Sm. The external walls of the radioactive nanocapsules are functionalized through arylation reaction, to introduce hydrophilic chains and increase the water dispersibility of CNTs. The organ biodistribution profiles of the nanocapsules up to 24 h are assessed in naïve mice and different tumor modelsin vivo. By quantitative γ-counting,153SmCl3@MWCNTs-NH2exhibite high accumulation in organs without leakage of the internal radioactive material to the bloodstream. In the treated mice, highest uptake is detected in the lung followed by the liver and spleen. Presence of tumors in brain or lung does not increase percentage accumulation of153SmCl3@MWCNTs-NH2in the respective organs, suggesting the absence of the enhanced permeation and retention effect. This study presents a chemical functionalization protocol that is rapid (∼one hour) and can be applied to filled radioactive multi-walled carbon nanocapsules to improve their water dispersibility for systemic administration for their use in targeted radiotherapy. © The Royal Society of Chemistry 2021.

  • Ga2O3 and Related Ultra‐Wide Bandgap Power Semiconductor Oxides: New Energy Electronics Solutions for CO2 Emission Mitigation

    Chi Z., Asher J.J., Jennings M.R., Chikoidze E., Pérez‐tomás A. Materials; 15 (3, 1164) 2022. 10.3390/ma15031164. IF: 3.623

    Advanced Electronic Materials and Devices

    Currently, a significant portion (~50%) of global warming emissions, such as CO2, are related to energy production and transportation. As most energy usage will be electrical (as well as transportation), the efficient management of electrical power is thus central to achieve the XXI century climatic goals. Ultra‐wide bandgap (UWBG) semiconductors are at the very frontier of electronics for energy management or energy electronics. A new generation of UWBG semiconductors will open new territories for higher power rated power electronics and solar‐blind deeper ultraviolet optoelectronics. Gallium oxide—Ga2O3 (4.5–4.9 eV), has recently emerged pushing the limits set by more conventional WBG (~3 eV) materials, such as SiC and GaN, as well as for transparent conducting oxides (TCO), such asIn2O3, ZnO and SnO2, to name a few. Indeed, Ga2O3 as the first oxide used as a semiconductor for power electronics, has sparked an interest in oxide semiconductors to be investigated (oxides represent the largest family of UWBG). Among these new power electronic materials, AlxGa1‐xO3 may provide high‐power heterostructure electronic and photonic devices at bandgaps far beyond all materials available today (~8 eV) or ZnGa2O4 (~5 eV), enabling spinel bipolar energy electronics for the first time ever. Here, we review the state‐of‐the‐art and prospects of some ultra‐wide bandgap oxide semiconductor arising technologies as promising innovative material solutions towards a sustainable zero emission society. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

  • Giant valley-polarized spin splittings in magnetized Janus Pt dichalcogenides

    Sattar S., Larsson J.A., Canali C.M., Roche S., Garcia J.H. Physical Review B; 105 (4, A100) 2022. 10.1103/PhysRevB.105.L041402. IF: 4.036

    Theoretical and Computational Nanoscience

    We reveal giant proximity-induced magnetism and valley-polarization effects in Janus Pt dichalcogenides (such as SPtSe), when bound to the europium oxide (EuO) substrate. Using first-principles simulations, it is surprisingly found that the charge redistribution, resulting from proximity with EuO, leads to the formation of two K and K′ valleys in the conduction bands. Each of these valleys displays its own spin polarization and a specific spin texture dictated by broken inversion and time-reversal symmetries, and valley-exchange and Rashba splittings as large as hundreds of meV. This provides a platform for exploring spin-valley physics in low-dimensional semiconductors, with potential spin transport mechanisms such as spin-orbit torques much more resilient to disorder and temperature effects. © 2022 American Physical Society.

  • Have mysterious topological valley currents been observed in graphene superlattices?

    Roche S., Power S.R., Nikolić B.K., García J.H., Jauho A.-P. JPhys Materials; 5 (2, 021001) 2022. 10.1088/2515-7639/ac452a. IF: 0.000

    Theoretical and Computational Nanoscience

    We provide a critical discussion concerning the claim of topological valley currents, driven by a global Berry curvature and valley Hall effect proposed in recent literature. After pointing out a major inconsistency of the theoretical scenario proposed to interpret giant nonlocal resistance, we discuss various possible alternative explanations and open directions of research to solve the mystery of nonlocal transport in graphene superlattices. © 2022 The Author(s).

  • Heat dissipation in few-layer MoS2and MoS2/hBN heterostructure

    Arrighi A., Del Corro E., Urrios D.N., Costache M.V., Sierra J.F., Watanabe K., Taniguchi T., Garrido J.A., Valenzuela S.O., Sotomayor Torres C.M., Sledzinska M. 2D Materials; 9 (1, 015005) 2022. 10.1088/2053-1583/ac2e51. IF: 7.103

    Physics and Engineering of Nanodevices | Phononic and Photonic Nanostructures | Advanced Electronic Materials and Devices

    State-of-the-art fabrication and characterisation techniques have been employed to measure the thermal conductivity of suspended, single-crystalline MoS2 and MoS2/hBN heterostructures. Two-laser Raman scattering thermometry was used combined with real time measurements of the absorbed laser power. Measurements on MoS2 layers with thicknesses of 5 and 14 nm exhibit thermal conductivity in the range between 12 Wm-1 K-1 and 24 Wm-1 K-1. Additionally, after determining the thermal conductivity of the latter MoS2 sample, an hBN flake was transferred onto it and the effective thermal conductivity of the heterostructure was subsequently measured. Remarkably, despite that the thickness of the hBN layer was less than a hal of the thickness of the MoS2 layer, the heterostructure showed an almost eight-fold increase in the thermal conductivity, being able to dissipate more than ten times the laser power without any visible sign of damage. These results are consistent with a high thermal interface conductance G between MoS2 and hBN and an efficient in-plane heat spreading driven by hBN. Indeed, we estimate G ∼ 70 MW m-2 K-1 for hBN layer thermal conductivity of 450 Wm-1 K-1 which is significantly higher than previously reported values. Our work therefore demonstrates that the insertion of hBN layers in potential MoS2-based devices holds the promise for efficient thermal management. © 2021 IOP Publishing Ltd.

  • Highly-Scattering Cellulose-Based Films for Radiative Cooling

    Jaramillo-Fernandez J., Yang H., Schertel L., Whitworth G.L., Garcia P.D., Vignolini S., Sotomayor-Torres C.M. Advanced Science; 9 (8, 2104758) 2022. 10.1002/advs.202104758. IF: 16.806

    Phononic and Photonic Nanostructures

    Passive radiative cooling (RC) enables the cooling of objects below ambient temperature during daytime without consuming energy, promising to be a game changer in terms of energy savings and CO2 reduction. However, so far most RC surfaces are obtained by energy-intensive nanofabrication processes or make use of unsustainable materials. These limitations are overcome by developing cellulose films with unprecedentedly low absorption of solar irradiance and strong mid-infrared (mid-IR) emittance. In particular, a cellulose-derivative (cellulose acetate) is exploited to produce porous scattering films of two different thicknesses, L ≈ 30 µm (thin) and L ≈ 300 µm (thick), making them adaptable to above and below-ambient cooling applications. The thin and thick films absorb only (Formula presented.) of the solar irradiance, which represents a net cooling power gain of at least 17 W m−2, compared to state-of-the-art cellulose-based radiative-cooling materials. Field tests show that the films can reach up to ≈5 °C below ambient temperature, when solar absorption and conductive/convective losses are minimized. Under dryer conditions (water column = 1 mm), it is estimated that the films can reach average minimum temperatures of ≈7–8 °C below the ambient. The work presents an alternative cellulose-based material for efficient radiative cooling that is simple to fabricate, cost-efficient and avoids the use of polluting materials. © 2022 The Authors. Advanced Science published by Wiley-VCH GmbH

  • How Does Immunomodulatory Nanoceria Work? ROS and Immunometabolism

    Ernst L.M., Puntes V. Frontiers in immunology; 13: 750175. 2022. 10.3389/fimmu.2022.750175. IF: 7.561

    Inorganic Nanoparticles

    Dysregulation of the immune system is associated with an overproduction of metabolic reactive oxygen species (ROS) and consequent oxidative stress. By buffering excess ROS, cerium oxide (CeO2) nanoparticles (NPs) (nanoceria) not only protect from oxidative stress consequence of inflammation but also modulate the immune response towards inflammation resolution. Immunomodulation is the modulation (regulatory adjustment) of the immune system. It has natural and human-induced forms, and it is part of immunotherapy, in which immune responses are induced, amplified, attenuated, or prevented according to therapeutic goals. For decades, it has been observed that immune cells transform from relative metabolic quiescence to a highly active metabolic state during activation(1). These changes in metabolism affect fate and function over a broad range of timescales and cell types, always correlated to metabolic changes closely associated with mitochondria number and morphology. The question is how to control the immunochemical potential, thereby regulating the immune response, by administering cellular power supply. In this regard, immune cells show different general catabolic modes relative to their activation status, linked to their specific functions (maintenance, scavenging, defense, resolution, and repair) that can be correlated to different ROS requirements and production. Properly formulated, nanoceria is highly soluble, safe, and potentially biodegradable, and it may overcome current antioxidant substances limitations and thus open a new era for human health management. Copyright © 2022 Ernst and Puntes.

  • Improved performance and stability of perovskite solar modules by interface modulating with graphene oxide crosslinked CsPbBr3quantum dots

    Zhang S., Guo R., Zeng H., Zhao Y., Liu X., You S., Li M., Luo L., Lira-Cantu M., Li L., Liu F., Zheng X., Liao G., Li X. Energy and Environmental Science; 15 (1): 244 - 253. 2022. 10.1039/d1ee01778k. IF: 38.532

    Nanostructured Materials for Photovoltaic Energy

    Perovskite solar cells (PSCs) are one of the most prominent photovoltaic technologies. However, PSCs still encounter great challenges of scaling up from laboratorial cells to industrial modules without serious performance loss while maintaining excellent long-term stability, owing to the resistive losses and extra instability factors that scale quadratically with the device area. Here, we manifest a concept of multifunctional interface modulation for highly efficient and stable perovskite solar modules (PSMs). The advisably designed multifunctional interface modulator GO/QD crosslinks the CsPbBr3 perovskite quantum dots (QDs) on the conductive graphene oxide (GO) surfaces, which significantly improve charge transport and energy band alignment at the perovskite/hole transporting layer interface to reduce the charge transport resistance while passivating the surface defects of the perovskite to inhibit carrier recombination resistive losses. Moreover, the GO/QD interlayer acts as a robust permeation barrier that modulates the undesirable interfacial ion and moisture diffusion. Consequently, we adopt a scalable vacuum flash-assisted solution processing (VASP) method to achieve a certified stabilized power output efficiency of 17.85% (lab-measured champion efficiency of 18.55%) for the mini-modules. The encapsulated PSMs achieve over 90% of their initial efficiency after continuous operation under 1 sun illumination and the damp heat test at 85 °C, respectively. This journal is © The Royal Society of Chemistry.

  • Innate but Not Adaptive Immunity Regulates Lung Recovery from Chronic Exposure to Graphene Oxide Nanosheets

    Loret T., de Luna L.A.V., Fordham A., Arshad A., Barr K., Lozano N., Kostarelos K., Bussy C. Advanced Science; 2022. 10.1002/advs.202104559. IF: 16.806


    Graphene has drawn a lot of interest in the material community due to unique physicochemical properties. Owing to a high surface area to volume ratio and free oxygen groups, the oxidized derivative, graphene oxide (GO) has promising potential as a drug delivery system. Here, the lung tolerability of two distinct GO varying in lateral dimensions is investigated, to reveal the most suitable candidate platform for pulmonary drug delivery. Following repeated chronic pulmonary exposure of mice to GO sheet suspensions, the innate and adaptive immune responses are studied. An acute and transient influx of neutrophils and eosinophils in the alveolar space, together with the replacement of alveolar macrophages by interstitial ones and a significant activation toward anti-inflammatory subsets, are found for both GO materials. Micrometric GO give rise to persistent multinucleated macrophages and granulomas. However, neither adaptive immune response nor lung tissue remodeling are induced after exposure to micrometric GO. Concurrently, milder effects and faster tissue recovery, both associated to a faster clearance from the respiratory tract, are found for nanometric GO, suggesting a greater lung tolerability. Taken together, these results highlight the importance of dimensions in the design of biocompatible 2D materials for pulmonary drug delivery system. © 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.

  • Interference effects in one-dimensional moiré crystals

    Wittemeier N., Verstraete M.J., Ordejón P., Zanolli Z. Carbon; 186: 416 - 422. 2022. 10.1016/j.carbon.2021.10.028. IF: 9.594

    Theory and Simulation

    Interference effects in finite sections of one-dimensional moiré crystals are investigated using a Landauer-Büttiker formalism within the tight-binding approximation. We explain interlayer transport in double-wall carbon nanotubes and design a predictive model. Wave function interference is visible at the mesoscale: in the strong coupling regime, as a periodic modulation of quantum conductance and emergent localized states; in the localized-insulating regime, as a suppression of interlayer transport, and oscillations of the density of states. These results could be exploited to design quantum electronic devices. © 2021 The Authors

  • Intranasal Administration of Catechol-Based Pt(IV) Coordination Polymer Nanoparticles for Glioblastoma Therapy

    Mao X., Calero-Pérez P., Montpeyó D., Bruna J., Yuste V.J., Candiota A.P., Lorenzo J., Novio F., Ruiz-Molina D. Nanomaterials; 12 (7, 1221) 2022. 10.3390/nano12071221. IF: 5.076

    Nanostructured Functional Materials

    Cisplatin has been described as a potent anticancer agent for decades. However, in the case of glioblastomas, it is only considered a rescue treatment applied after the failure of second-line treatments. Herein, based on the versatility offered by coordination chemistry, we engineered nanoparticles by reaction of a platinum (IV) prodrug and iron metal ions showing in vitro dual pH-and redox-sensitivity, controlled release and comparable cytotoxicity to cisplatin against HeLa and GL261 cells. In vivo intranasal administration in orthotopic preclinical GL261 glioblastoma tumor-bearing mice demonstrated increased accumulation of platinum in tumors, leading in some cases to complete cure and prolonged survival of the tested cohort. This was corroborated by a magnetic resonance imaging follow-up, thus opening new opportunities for intranasal glioblastoma therapies while minimizing side effects. The findings derived from this research showed the potentiality of this approach as a novel therapy for glioblastoma treatment. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

  • Introducing surface functionality on thermoformed polymeric films

    Sáez-Comet C., Muntada O., Francone A., Lozano N., Fernandez-Regulez M., Puiggali J., Kehagias N., Sotomayor Torres C.M., Perez-Murano F. Micro and Nano Engineering; 14 (100112) 2022. 10.1016/j.mne.2022.100112. IF: 0.000

    Phononic and Photonic Nanostructures

    We present a fabrication process for the production of 3-dimensional micro-structured polymeric films. The microstructures are fabricated in a single step using thermal nanoimprint lithography as patterning technique. The micro-structured polymer films are then transformed into a 3D shape by means of a plug-assisted thermoforming process, while keeping the functionality of the micro-patterned areas. The preserved functionality is characterized by water contact angle measurements, while the deformation of the micro-structured topographies due to the thermoforming process is analyzed using confocal microscopy and Digital Image Correlation (DIC) techniques. This combined fabrication process represents a promising solution to complement in-mold decoration approaches, enabling the production of new functional surfaces. As the microstructures are fabricated by means of a mechanical modification of the surface, without the need of chemical treatments or coatings, the presented technique represents a promising, simple and green solution, suitable for the industrial fabrication of 3D nonplanar shaped functional surfaces. © 2022

  • Label-free and reagentless electrochemical genosensor based on graphene acid for meat adulteration detection

    Flauzino J.M.R., Nguyen E.P., Yang Q., Rosati G., Panáček D., Brito-Madurro A.G., Madurro J.M., Bakandritsos A., Otyepka M., Merkoçi A. Biosensors and Bioelectronics; 195 (113628) 2022. 10.1016/j.bios.2021.113628. IF: 10.618

    Nanobioelectronics and Biosensors

    With the increased demand for beef in emerging markets, the development of quality-control diagnostics that are fast, cheap and easy to handle is essential. Especially where beef must be free from pork residues, due to religious, cultural or allergic reasons, the availability of such diagnostic tools is crucial. In this work, we report a label-free impedimetric genosensor for the sensitive detection of pork residues in meat, by leveraging the biosensing capabilities of graphene acid - a densely and selectively functionalized graphene derivative. A single stranded DNA probe, specific for the pork mitochondrial genome, was immobilized onto carbon screen-printed electrodes modified with graphene acid. It was demonstrated that graphene acid improved the charge transport properties of the electrode, following a simple and rapid electrode modification and detection protocol. Using non-faradaic electrochemical impedance spectroscopy, which does not require any electrochemical indicators or redox pairs, the detection of pork residues in beef was achieved in less than 45 min (including sample preparation), with a limit of detection of 9% w/w pork content in beef samples. Importantly, the sample did not need to be purified or amplified, and the biosensor retained its performance properties unchanged for at least 4 weeks. This set of features places the present pork DNA sensor among the most attractive for further development and commercialization. Furthermore, it paves the way for the development of sensitive and selective point-of-need sensing devices for label-free, fast, simple and reliable monitoring of meat purity. © 2021

  • Label-Free Plasmonic Biosensor for Rapid, Quantitative, and Highly Sensitive COVID-19 Serology: Implementation and Clinical Validation

    Calvo-Lozano O., Sierra M., Soler M., Estévez M.C., Chiscano-Camón L., Ruiz-Sanmartin A., Ruiz-Rodriguez J.C., Ferrer R., González-López J.J., Esperalba J., Fernández-Naval C., Bueno L., López-Aladid R., Torres A., Fernández-Barat L., Attoumani S., Charrel R., Coutard B., Lechuga L.M. Analytical Chemistry; 94 (2): 975 - 984. 2022. 10.1021/acs.analchem.1c03850. IF: 6.986

    NanoBiosensors and Bioanalytical Applications

    Serological tests are essential for the control and management of COVID-19 pandemic (diagnostics and surveillance, and epidemiological and immunity studies). We introduce a direct serological biosensor assay employing proprietary technology based on plasmonics, which offers rapid (<15 min) identification and quantification of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies in clinical samples, without signal amplification. The portable plasmonic device employs a custom-designed multiantigen (RBD peptide and N protein) sensor biochip and reaches detection limits in the low ng mL–1 range employing polyclonal antibodies. It has also been implemented employing the WHO-approved anti-SARS-CoV-2 immunoglobulin standard. A clinical validation with COVID-19 positive and negative samples (n = 120) demonstrates its excellent diagnostic sensitivity (99%) and specificity (100%). This positions our biosensor as an accurate and easy-to-use diagnostics tool for rapid and reliable COVID-19 serology to be employed both at laboratory and decentralized settings for the disease management and for the evaluation of immunological status during vaccination or treatment. © 2021 The Authors. Published by American Chemical Society

  • Low-Cost, User-Friendly, All-Integrated Smartphone-Based Microplate Reader for Optical-Based Biological and Chemical Analyses

    Bergua J.F., Álvarez-Diduk R., Idili A., Parolo C., Maymó M., Hu L., Merkoçi A. Analytical Chemistry; 94 (2): 1271 - 1285. 2022. 10.1021/acs.analchem.1c04491. IF: 6.986

    Nanobioelectronics and Biosensors

    The quantitative detection of different molecular targets is of utmost importance for a variety of human activities, ranging from healthcare to environmental studies. Bioanalytical methods have been developed to solve this and to achieve the quantification of multiple targets from small volume samples. Generally, they can be divided into two different classes: point of care (PoC) and laboratory-based approaches. The former is rapid, low-cost, and user-friendly; however, the majority of the tests are semiquantitative, lacking in specificity and sensitivity. On the contrary, laboratory-based approaches provide high sensitivity and specificity, but the bulkiness of experimental instruments and complicated protocols hamper their use in resource-limited settings. In response, here we propose a smartphone-based device able to support laboratory-based optical techniques directly at the point of care. Specifically, we designed and fabricated a portable microplate reader that supports colorimetric, fluorescence, luminescence, and turbidity analyses. To demonstrate the potential of the device, we characterized its analytical performance by detecting a variety of relevant molecular targets (ranging from antibodies, toxins, drugs, and classic fluorophore dyes) and we showed how the estimated results are comparable to those obtained from a commercial microplate reader. Thanks to its low cost (<$300), portability (27 cm [length] × 18 cm [width] × 7 cm [height]), commercially available components, and open-source-based system, we believe it represents a valid approach to bring high-precision laboratory-based analysis at the point of care. © 2022 The Authors. Published by American Chemical Society

  • Magnetic properties of coordination clusters with {Mn4} and {Co4} antiferromagnetic cores

    Achilli S., Besson C., He X., Ordejón P., Meyer C., Zanolli Z. Physical Chemistry Chemical Physics; 24 (6): 3780 - 3787. 2022. 10.1039/d1cp03904k. IF: 3.676

    Theory and Simulation

    We present a joint experimental and theoretical characterization of the magnetic properties of coordination clusters with an antiferromagnetic core of four magnetic ions. Two different compounds are analyzed, with Co and Mn ions in the core. While both molecules are antiferromagnetic, they display different sensitivities to external magnetic field, according to the different atomic magnetic moments and strength of the intra-molecular magnetic couplings. In particular, the dependence of the magnetization versus field of the two molecules switches with temperature: at low temperature the magnetization is smaller in {Mn4} than in Co4, while the opposite happens at high temperature. Through a detailed analysis of the electronic and magnetic properties of the two compounds we identify a stronger magnetic interaction between the magnetic ions in {Mn4} with respect to {Co4}. Moreover {Co4} displays not negligible spin-orbit related effects that could affect the spin lifetime in future antiferromagnetic spintronic applications. We highlight the necessity to account for these spin-orbit effects together with electronic correlation effects for a reliable description of these compounds. © the Owner Societies.

  • Magnetism, symmetry and spin transport in van der Waals layered systems

    Kurebayashi H., Garcia J.H., Khan S., Sinova J., Roche S. Nature Reviews Physics; 4 (3): 150 - 166. 2022. 10.1038/s42254-021-00403-5. IF: 31.068

    Theoretical and Computational Nanoscience

    The discovery of an ever-increasing family of atomic layered magnetic materials, together with the already established vast catalogue of strong spin–orbit coupling and topological systems, calls for some guiding principles to tailor and optimize novel spin transport and optical properties at their interfaces. Here, we focus on the latest developments in both fields that have brought them closer together and make them ripe for future fruitful synergy. After outlining fundamentals on van der Waals magnetism and spin–orbit coupling effects, we discuss how their coexistence, manipulation and competition could ultimately establish new ways to engineer robust spin textures and drive the generation and dynamics of spin current and magnetization switching in 2D-materials-based van der Waals heterostructures. Grounding our analysis on existing experimental results and theoretical considerations, we draw a prospective analysis about how intertwined magnetism and spin–orbit torque phenomena combine at interfaces with well-defined symmetries and how this dictates the nature and figures of merit of spin–orbit torque and angular momentum transfer. This will serve as a guiding role in designing future non-volatile memory devices that utilize the unique properties of 2D materials with the spin degree of freedom. © 2022, Springer Nature Limited.

  • Manipulation of spin transport in graphene/transition metal dichalcogenide heterobilayers upon twisting

    Pezo A., Zanolli Z., Wittemeier N., Ordejón P., Fazzio A., Roche S., Garcia J.H. 2D Materials; 9 (1, 015008) 2022. 10.1088/2053-1583/ac3378. IF: 7.103

    Theory and Simulation | Theoretical and Computational Nanoscience

    Proximity effects between layered materials trigger a plethora of novel and exotic quantum transport phenomena. Besides, the capability to modulate the nature and strength of proximity effects by changing crystalline and interfacial symmetries offers a vast playground to optimize physical properties of relevance for innovative applications. In this work, we use large-scale first principles calculations to demonstrate that strain and twist-angle strongly vary the spin–orbit coupling (SOC) in graphene/transition metal dichalcogenide heterobilayers. Such a change results in a modulation of the spin relaxation times by up to two orders of magnitude. Additionally, the relative strengths of valley-Zeeman and Rashba SOC can be tailored upon twisting, which can turn the system into an ideal Dirac–Rashba regime or generate transitions between topological states of matter. These results shed new light on the debated variability of SOC and clarify how lattice deformations can be used as a knob to control spin transport. Our outcomes also suggest complex spin transport in polycrystalline materials, due to the random variation of grain orientation, which could reflect in large spatial fluctuations of SOC fields. © 2021 IOP Publishing Ltd

  • Merging of superfluid helium nanodroplets with vortices

    Escartín J.M., Ancilotto F., Barranco M., Pi M. Physical Review B; 105 (2, 024511) 2022. 10.1103/PhysRevB.105.024511. IF: 4.036

    Theory and Simulation

    Within density functional theory, we have investigated the coalescence dynamics of two superfluid helium nanodroplets hosting vortex lines in different relative orientations, which are drawn towards each other by the Van der Waals mutual attraction. We have found a rich phenomenology depending on how the vortex lines are oriented. In particular, when a vortex and antivortex lines are present in the merging droplets, a dark soliton develops at the droplet contact region, which eventually decays into vortex rings. Reconnection events are observed between the vortex lines or rings, leading to the creation of more vortices. Our simulations show the interplay between vortex creation and reconnections, as well as the effect of the droplet surface which pins the vortex ends and, by reflecting short-wavelength excitations produced by the interactions between vortices, strongly affects the droplet final state. Additional vorticity is nucleated in the proximity of surface indentations produced in the course of the dynamics, which in turn interact with other vortices present in the droplets. These effects, obviously absent in the case of bulk liquid helium, show that the droplet surface may act as a multiplier of vortex reconnections. The analysis of the energy spectrum shows that vortex-antivortex ring annihilation, as well as vortex-antivortex reconnections, yields roton bursts of different intensity. © 2022 American Physical Society.

  • Metabolomics for personalized medicine: the input of analytical chemistry from biomarker discovery to point-of-care tests

    Castelli F.A., Rosati G., Moguet C., Fuentes C., Marrugo-Ramírez J., Lefebvre T., Volland H., Merkoçi A., Simon S., Fenaille F., Junot C. Analytical and Bioanalytical Chemistry; 414 (2): 759 - 789. 2022. 10.1007/s00216-021-03586-z. IF: 4.142

    Nanobioelectronics and Biosensors

    Metabolomics refers to the large-scale detection, quantification, and analysis of small molecules (metabolites) in biological media. Although metabolomics, alone or combined with other omics data, has already demonstrated its relevance for patient stratification in the frame of research projects and clinical studies, much remains to be done to move this approach to the clinical practice. This is especially true in the perspective of being applied to personalized/precision medicine, which aims at stratifying patients according to their risk of developing diseases, and tailoring medical treatments of patients according to individual characteristics in order to improve their efficacy and limit their toxicity. In this review article, we discuss the main challenges linked to analytical chemistry that need to be addressed to foster the implementation of metabolomics in the clinics and the use of the data produced by this approach in personalized medicine. First of all, there are already well-known issues related to untargeted metabolomics workflows at the levels of data production (lack of standardization), metabolite identification (small proportion of annotated features and identified metabolites), and data processing (from automatic detection of features to multi-omic data integration) that hamper the inter-operability and reusability of metabolomics data. Furthermore, the outputs of metabolomics workflows are complex molecular signatures of few tens of metabolites, often with small abundance variations, and obtained with expensive laboratory equipment. It is thus necessary to simplify these molecular signatures so that they can be produced and used in the field. This last point, which is still poorly addressed by the metabolomics community, may be crucial in a near future with the increased availability of molecular signatures of medical relevance and the increased societal demand for participatory medicine. Graphical abstract: [Figure not available: see fulltext.] © 2021, The Author(s).

  • Metal- and Alloy-Based Core-Shell Particles in Nitrate Senary Salt with Low Thermal Hysteresis for Solar Thermal Energy Storage

    Chen K., Chung F.-J., Lin Y.-L., Lee Y.-T., Rodríguez-Laguna M.D.R., Manikandan A., Lu M.-C., Chueh Y.-L. ACS Applied Energy Materials; 5 (3): 2697 - 2705. 2022. 10.1021/acsaem.1c02919. IF: 0.000

    Novel Energy-Oriented Materials

    In this work, the microencapsulated phase change materials, Sn/amorphous-carbon (Sn/a-C), and SnBi/amorphous carbon (SnBi/a-C) microparticles (MPs) were successfully synthesized. The thermal stabilities of Sn/a-C and SnBi/a-C core-shell MPs were verified by cycling tests, and stable latent heats of 56 and 45.7 J/g were obtained for Sn/a-C and SnBi/a-C MPs, respectively. Compared to the high melting point of 231 °C and large thermal hysteresis (TH) of ∼106 °C for the Sn/a-C MPs, the SnBi/a-C MPs exhibited a lower melting point of 125 °C and a smaller TH of 20 °C. The nitrate senary salt with a lower melting point of ∼75 °C than that of the commercial HITEC salt (melting point of ∼142 °C) was also synthesized to enlarge the working temperature range of the working fluid in a solar thermal power plant and to demonstrate the latent heat-enhanced thermal energy storage using the SnBi/a-C MPs. The heat capacity can be enhanced by 200% by doping with 20 wt % Sn/a-C MPs into the HITEC salt, and it can be enhanced by 734% by doping with 20 wt % SnBi/a-C MPs into the senary salt. In addition, the viscosities of the HITEC salt and senary salt doped with the Sn/a-C and SnBi/a-C MPs were not appreciably raised by doping with the MPs. The various approaches accomplished in this work demonstrate (1) enhancing heat capacity of the working fluid by exploiting the latent heats of the embedded MPs; (2) lowering the TH of the MPs by using the alloy metal particles; and (3) extending the working temperature range by synthesizing the senary salt. These approaches could be applied for enhancing energy storage in solar thermal power plants and facilitating waste heat recovery. © 2022 American Chemical Society. All rights reserved.

  • Metal–Organic Polyhedra as Building Blocks for Porous Extended Networks

    Khobotov-Bakishev A., Hernández-López L., von Baeckmann C., Albalad J., Carné-Sánchez A., Maspoch D. Advanced Science; 2022. 10.1002/advs.202104753. IF: 16.806

    Supramolecular NanoChemistry and Materials

    Metal–organic polyhedra (MOPs) are a subclass of coordination cages that can adsorb and host species in solution and are permanently porous in solid-state. These characteristics, together with the recent development of their orthogonal surface chemistry and the assembly of more stable cages, have awakened the latent potential of MOPs to be used as building blocks for the synthesis of extended porous networks. This review article focuses on exploring the key developments that make the extension of MOPs possible, highlighting the most remarkable examples of MOP-based soft materials and crystalline extended frameworks. Finally, the article ventures to offer future perspectives on the exploitation of MOPs in fields that still remain ripe toward the use of such unorthodox molecular porous platforms. © 2022 The Authors. Advanced Science published by Wiley-VCH GmbH

  • MOF-Derived Ultrathin Cobalt Molybdenum Phosphide Nanosheets for Efficient Electrochemical Overall Water Splitting

    Wang X., Yang L., Xing C., Han X., Du R., He R., Guardia P., Arbiol J., Cabot A. Nanomaterials; 12 (7, 1098) 2022. 10.3390/nano12071098. IF: 5.076

    Advanced Electron Nanoscopy

    The development of high-performance and cost-effective earth-abundant transition metal-based electrocatalysts is of major interest for several key energy technologies, including water splitting. Herein, we report the synthesis of ultrathin CoMoP nanosheets through a simple ion etching and phosphorization method. The obtained catalyst exhibits outstanding electrocatalytic activity and stability towards oxygen and hydrogen evolution reactions (OER and HER), with overpotentials down to 273 and 89 mV at 10 mA cm−2, respectively. The produced CoMoP nanosheets are also characterized by very small Tafel slopes, 54.9 and 69.7 mV dec−1 for OER and HER, respectively. When used as both cathode and anode electrocatalyst in the overall water splitting reaction, CoMoP-based cells require just 1.56 V to reach 10 mA cm−2 in alkaline media. This outstanding performance is at-tributed to the proper composition, weak crystallinity and two-dimensional nanosheet structure of the electrocatalyst. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

  • Novel Sensing Algorithm for Linear Read-Out of Bimodal Waveguide Interferometric Biosensors

    Bassols-Cornudella B., Ramirez-Priego P., Soler M., Estevez M.-C., Luis-Ravelo H.J.D., Cardenosa-Rubio M., Lechuga L.M. Journal of Lightwave Technology; 40 (1): 237 - 244. 2022. 10.1109/JLT.2021.3118103. IF: 4.142

    NanoBiosensors and Bioanalytical Applications

    Biosensors employing photonics integrated circuits, and specifically those that rely on interferometric evanescent wave working principles, have outstanding performances due to the extreme sensitivity exhibited in one-step and direct assay, without the need of amplification. Within the interferometric configurations, the Bimodal Waveguide (BiMW) interferometric sensor stands out due to its demonstrated sensitivity for real-life applications and the simplicity of its design. To overcome the ambiguities that arise from the periodic nature of interferometric read-outs, a new all-optical modulation and the subsequent trigonometry-based algorithm have been proposed and applied to the BiMW biosensor. This new algorithm has been successfully employed for the selective identification and quantification of the external Spike (S) protein of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Our biosensing results from this simple, quick, and user-friendly method demonstrate high sensitivity and specificity and pave the way towards a point-of-care device for general use. © 1983-2012 IEEE.

  • Observation of slow light in glide-symmetric photonic-crystal waveguides

    Patil C.M., Arregui G., Mechlenborg M., Zhou X., Alaeian H., García P.D., Stobbe S. Optics Express; 30 (8): 12565 - 12575. 2022. 10.1364/OE.449221. IF: 3.894

    Phononic and Photonic Nanostructures

    We report optical transmission measurements on suspended silicon photonic-crystal waveguides, where one side of the photonic lattice is shifted by half a period along the waveguide axis. The combination of this glide symmetry and slow light leads to a strongly enhanced chiral light-matter interaction but the interplay between slow light and backscattering has not been investigated experimentally in such waveguides. We build photonic-crystal resonators consisting of glide-symmetric waveguides terminated by reflectors and use transmission measurements as well as evanescent coupling to map out the dispersion relation. We find excellent agreement with theory and measure group indices exceeding 90, implying significant potential for applications in slow-light devices and chiral quantum optics. By measuring resonators of different length, we assess the role of backscattering induced by fabrication imperfections and its intimate connection to the group index. © 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement Journal © 2022

  • On the thermoelectric properties of Nb-doped SrTiO3epitaxial thin films

    Chatterjee A., Lan Z., Christensen D.V., Bauitti F., Morata A., Chavez-Angel E., Sanna S., Castelli I.E., Chen Y., Tarancon A., Pryds N. Physical Chemistry Chemical Physics; 24 (6): 3741 - 3748. 2022. 10.1039/d1cp03679c. IF: 0.000

    Phononic and Photonic Nanostructures

    The exploration for thermoelectric thin films of complex oxides such as SrTiO3-based oxides is driven by the need for miniaturized harvesting devices for powering the Internet of Things (IoT). However, there is still not a clear consensus in the literature for the underlying influence of film thickness on thermoelectric properties. Here, we report the fabrication of epitaxial thin films of 6% Nb-doped SrTiO3 on (001) (LaAlO3)0.3(Sr2AlTaO6)0.7 (LSAT) single crystal using pulsed laser deposition (PLD) where the film thickness was varied from 2 nm to 68 nm. The thickness dependence shows a subtle increase of tetragonality of the thin film lattice and a gradual drop of the electrical conductivity, the density of charge carriers, and the thermoelectric Seebeck coefficient as the film thickness decreases. DFT-based calculations show that ∼2.8% increase in tetragonality results in an increased splitting between t2g and eg orbitals to ∼42.3 meV. However, experimentally observed tetragonality for films between 68 to 13 nm is only 0.06%. Hence, the effect of thickness on tetragonality is neglected. We have discussed the decrease of conductivity and the Seebeck coefficient based on the decrease of carriers and change in the scattering mechanism, respectively. © the Owner Societies.

  • Pharmacokinetics of PEGylated Gold Nanoparticles: In Vitro—In Vivo Correlation

    Dubaj T., Kozics K., Sramkova M., Manova A., Bastús N.G., Moriones O.H., Kohl Y., Dusinska M., Runden-Pran E., Puntes V., Nelson A., Gabelova A., Simon P. Nanomaterials; 12 (3, 511) 2022. 10.3390/nano12030511. IF: 5.076

    Inorganic Nanoparticles

    Data suitable for assembling a physiologically-based pharmacokinetic (PBPK) model for nanoparticles (NPs) remain relatively scarce. Therefore, there is a trend in extrapolating the results of in vitro and in silico studies to in vivo nanoparticle hazard and risk assessment. To evaluate the reliability of such approach, a pharmacokinetic study was performed using the same polyethylene glycol-coated gold nanoparticles (PEG-AuNPs) in vitro and in vivo. As in vitro models, human cell lines TH1, A549, Hep G2, and 16HBE were employed. The in vivo PEG-AuNP biodistribution was assessed in rats. The internalization and exclusion of PEG-AuNPs in vitro were modeled as first-order rate processes with the partition coefficient describing the equilibrium distribution. The pharmacokinetic parameters were obtained by fitting the model to the in vitro data and subsequently used for PBPK simulation in vivo. Notable differences were observed in the internalized amount of Au in individual cell lines compared to the corresponding tissues in vivo, with the highest found for renal TH1 cells and kidneys. The main reason for these discrepancies is the absence of natural barriers in the in vitro conditions. Therefore, caution should be exercised when extrapolating in vitro data to predict the in vivo NP burden and response to exposure. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

  • Role of pO2 and film microstructure on the memristive properties of La2NiO4+δ/LaNiO3−δ bilayers

    Maas K., Wulles C., Caicedo Roque J.M., Ballesteros B., Lafarge V., Santiso J., Burriel M. Journal of Materials Chemistry A; 10 (12): 6523 - 6530. 2022. 10.1039/d1ta10296f. IF: 12.732

    Nanomaterials Growth Unit | Electron Microscopy Unit

    LaNiO3/La2NiO4 bilayers deposited at varying pO2 conditions resulted in remarkable differences in film microstructure and cell parameters, directly affecting the electrical behaviour of Pt/LaNiO3/La2NiO4/Pt devices. The devices deposited at low pO2 showed the largest memristance. We propose this is due to the formation of a p-type Schottky contact between LaNiO3 and La2NiO4, where the extent of its carrier depletion width can be modulated by the electric-field induced drift of interstitial oxygen ions acting as mobile acceptor dopants in La2NiO4 © 2022 The Royal Society of Chemistry

  • Room temperature aqueous-based synthesis of copper-doped lead sulfide nanoparticles for thermoelectric application

    Li M., Liu Y., Zhang Y., Chang C., Zhang T., Yang D., Xiao K., Arbiol J., Ibáñez M., Cabot A. Chemical Engineering Journal; 433 (133837) 2022. 10.1016/j.cej.2021.133837. IF: 13.273

    Advanced Electron Nanoscopy

    A versatile, scalable, room temperature and surfactant-free route for the synthesis of metal chalcogenide nanoparticles in aqueous solution is detailed here for the production of PbS and Cu-doped PbS nanoparticles. Subsequently, nanoparticles are annealed in a reducing atmosphere to remove surface oxide, and consolidated into dense polycrystalline materials by means of spark plasma sintering. By characterizing the transport properties of the sintered material, we observe the annealing step and the incorporation of Cu to play a key role in promoting the thermoelectric performance of PbS. The presence of Cu allows improving the electrical conductivity by increasing the charge carrier concentration and simultaneously maintaining a large charge carrier mobility, which overall translates into record power factors at ambient temperature, 2.3 mWm-1K−2. Simultaneously, the lattice thermal conductivity decreases with the introduction of Cu, leading to a record high ZT = 0.37 at room temperature and ZT = 1.22 at 773 K. Besides, a record average ZTave = 0.76 is demonstrated in the temperature range 320–773 K for n-type Pb0.955Cu0.045S. © 2021 Elsevier B.V.

  • Room-Temperature Silicon Platform for GHz-Frequency Nanoelectro-Opto-Mechanical Systems

    Navarro-Urrios D., Colombano M.F., Arregui G., Madiot G., Pitanti A., Griol A., Makkonen T., Ahopelto J., Sotomayor-Torres C.M., Martínez A. ACS Photonics; 9 (2): 413 - 419. 2022. 10.1021/acsphotonics.1c01614. IF: 7.529

    Phononic and Photonic Nanostructures

    Nanoelectro-opto-mechanical systems enable the synergistic coexistence of electrical, mechanical, and optical signals on a chip to realize new functions. Most of the technology platforms proposed for the fabrication of these systems so far are not fully compatible with the mainstream CMOS technology, thus, hindering the mass-scale utilization. We have developed a CMOS technology platform for nanoelectro-opto-mechanical systems that includes piezoelectric interdigitated transducers for electronic driving of mechanical signals and nanocrystalline silicon nanobeams for an enhanced optomechanical interaction. Room-Temperature operation of devices at 2 GHz and with peak sensitivity down to 2.6 cavity phonons is demonstrated. Our proof-of-principle technology platform can be integrated and interfaced with silicon photonics, electronics, and MEMS devices and may enable multiple functions for coherent signal processing in the classical and quantum domains. ©

  • Site-Specific Axial Oxygen Coordinated FeN4 Active Sites for Highly Selective Electroreduction of Carbon Dioxide

    Zhang T., Han X., Liu H., Biset-Peiró M., Li J., Zhang X., Tang P., Yang B., Zheng L., Morante J.R., Arbiol J. Advanced Functional Materials; 2022. 10.1002/adfm.202111446. IF: 18.808

    Advanced Electron Nanoscopy

    Regulating the coordination environment via heteroatoms to break the symmetrical electronic structure of M-N4 active sites provides a promising route to engineer metal-nitrogen-carbon catalysts for electrochemical CO2 reduction reaction. However, it remains challenging to realize a site-specific introduction of heteroatoms at atomic level due to their energetically unstable nature. Here, this paper reports a facile route via using an oxygen- and nitrogen-rich metal–organic framework (MOF) (IRMOF-3) as the precursor to construct the Fe-O and Fe-N chelation, simultaneously, resulting in an atomically dispersed axial O-coordinated FeN4 active site. Compared to the FeN4 active sites without O coordination, the formed FeN4-O sites exhibit much better catalytic performance toward CO, reaching a maximum FECO of 95% at −0.50 V versus reversible hydrogen electrode. To the best of the authors’ knowledge, such performance exceeds that of the existing Fe-N-C-based catalysts derived from sole N-rich MOFs. Density functional theory calculations indicate that the axial O-coordination regulates the binding energy of intermediates in the reaction pathways, resulting in a smoother desorption of CO and increased energy for the competitive hydrogen production. © 2022 Wiley-VCH GmbH

  • Surface chemistry of metal-organic polyhedra

    Albalad J., Hernández-López L., Carné-Sánchez A., Maspoch D. Chemical Communications; 58 (15): 2443 - 2454. 2022. 10.1039/d1cc07034g. IF: 6.222

    Supramolecular NanoChemistry and Materials

    Metal-organic polyhedra (MOPs) are discrete, intrinsically-porous architectures that operate at the molecular regime and, owing to peripheral reactive sites, exhibit rich surface chemistry. Researchers have recently exploited this reactivity through post-synthetic modification (PSM) to generate specialised molecular platforms that may overcome certain limitations of extended porous materials. Indeed, the combination of modular solubility, orthogonal reactive sites, and accessible cavities yields a highly versatile molecular platform for solution to solid-state applications. In this feature article, we discuss representative examples of the PSM chemistry of MOPs, from proof-of-concept studies to practical applications, and highlight future directions for the MOP field. © The Royal Society of Chemistry.

  • Sustainable and Printable Nanocellulose-Based Ionogels as Gel Polymer Electrolytes for Supercapacitors

    González-Gil R.M., Borràs M., Chbani A., Abitbol T., Fall A., Aulin C., Aucher C., Martínez-Crespiera S. Nanomaterials; 12 (2, 273) 2022. 10.3390/nano12020273. IF: 5.076

    Novel Energy-Oriented Materials

    A new gel polymer electrolyte (GPE) based supercapacitor with an ionic conductivity up to 0.32–0.94 mS cm−2 has been synthesized from a mixture of an ionic liquid (IL) with nanocellulose (NC). The new NC-ionogel was prepared by combining the IL 1-ethyl-3-methylimidazolium dimethyl phosphate (EMIMP) with carboxymethylated cellulose nanofibers (CNFc) at different ratios (CNFc ratio from 1 to 4). The addition of CNFc improved the ionogel properties to become easily printable onto the electrode surface. The new GPE based supercapacitor cell showed good electrochemical performance with specific capacitance of 160 F g−1 and an equivalent series resistance (ESR) of 10.2 Ω cm−2 at a current density of 1 mA cm−2. The accessibility to the full capacitance of the device is demonstrated after the addition of CNFc in EMIMP compared to the pristine EMIMP (99 F g−1 and 14.7 Ω cm−2). © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

  • Synthesis and Validation of a Bioinspired Catechol-Functionalized Pt(IV) Prodrug for Preclinical Intranasal Glioblastoma Treatment

    Mao X., Wu S., Calero-Pérez P., Candiota A.P., Alfonso P., Bruna J., Yuste V.J., Lorenzo J., Novio F., Ruiz-Molina D. Cancers; 14 (2, 410) 2022. 10.3390/cancers14020410. IF: 6.639

    Nanostructured Functional Materials

    Glioblastoma is the most malignant and frequently occurring type of brain tumors in adults. Its treatment has been greatly hampered by the difficulty to achieve effective therapeutic concentration in the tumor sites due to its location and the blood–brain barrier. Intranasal administration has emerged as an alternative for drug delivery into the brain though mucopenetration, and rapid mucociliary clearance still remains an issue to be solved before its implementation. To address these issues, based on the intriguing properties of proteins secreted by mussels, polyphenol and catechol functionalization has already been used to promote mucopenetration, intranasal delivery and transport across the blood–brain barrier. Thus, herein we report the synthesis and study of complex 1, a Pt(IV) prodrug functionalized with catecholic moieties. This complex considerably augmented solubility in contrast to cisplatin and showed a comparable cytotoxic effect on cisplatin in HeLa, 1Br3G and GL261 cells. Furthermore, preclinical in vivo therapy using the intranasal administration route suggested that it can reach the brain and inhibit the growth of orthotopic GL261 glioblastoma. These results open new opportunities for catechol-bearing anticancer prodrugs in the treatment for brain tumors via intranasal administration. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

  • Tailored nano-columnar La2NiO4cathodes for improved electrode performance

    Stangl A., Riaz A., Rapenne L., Caicedo J.M., De Dios Sirvent J., Baiutti F., Jiménez C., Tarancón A., Mermoux M., Burriel M. Journal of Materials Chemistry A; 10 (5): 2528 - 2540. 2022. 10.1039/d1ta09110g. IF: 12.732

    Nanomaterials Growth Unit

    La2NiO4 is a very promising cathode material for intermediate and low temperature solid oxide cell applications, due to its good electronic and ionic conductivity, together with its high oxygen exchange activity with a low activation energy. Oxygen incorporation and transport in La2NiO4 (L2NO4) thin films are limited by surface reactions. Hence, tailoring the morphology is expected to lead to an overall improvement of the electrode performance. We report the growth of nano-architectured La2NiO4 thin film electrodes by Pulsed Injection Metal Organic Chemical Vapour Deposition (PI-MOCVD), achieving vertically gapped columns with a multi-fold active surface area, leading to much faster oxygen exchange. This nano-columnar structure is rooted in a dense bottom layer serving as a good electronic and ionic conduction pathway. The microstructure is tuned by modification of the growth temperature and characterised by SEM, TEM and XRD. We studied the effect of surface activity by electrical conductivity relaxation measurements in fully dense and nano-columnar La2NiO4 thin films of various thicknesses grown on several different single crystal substrates. Our results demonstrate that the increased surface area, in combination with the opening of different surface terminations, leads to a significant enhancement of the total exchange activity in our films with an optimized nano-architectured microstructure. This journal is © The Royal Society of Chemistry.

  • The elphbolt ab initio solver for the coupled electron-phonon Boltzmann transport equations

    Protik N.H., Li C., Pruneda M., Broido D., Ordejón P. npj Computational Materials; 8 (1, 28) 2022. 10.1038/s41524-022-00710-0. IF: 12.241

    Theory and Simulation

    elphbolt is a modern Fortran (2018 standard) code for efficiently solving the coupled electron–phonon Boltzmann transport equations from first principles. Using results from density functional and density functional perturbation theory as inputs, it can calculate the effect of the non-equilibrium phonons on the electronic transport (phonon drag) and non-equilibrium electrons on the phononic transport (electron drag) in a fully self-consistent manner and obeying the constraints mandated by thermodynamics. It can calculate the lattice, charge, and thermoelectric transport coefficients for the temperature gradient and electric fields, and the effect of the mutual electron–phonon drag on these transport properties. The code fully exploits the symmetries of the crystal and the transport-active window to allow the sampling of extremely fine electron and phonon wave vector meshes required for accurately capturing the drag phenomena. The coarray feature of modern Fortran, which offers native and convenient support for parallelization, is utilized. The code is compact, readable, well-documented, and extensible by design. © 2022, The Author(s).

  • Thermal Properties of Nanocrystalline Silicon Nanobeams

    Maire J., Chávez-Ángel E., Arregui G., Colombano M.F., Capuj N.E., Griol A., Martínez A., Navarro-Urrios D., Ahopelto J., Sotomayor-Torres C.M. Advanced Functional Materials; 32 (4, 2105767) 2022. 10.1002/adfm.202105767. IF: 18.808

    Phononic and Photonic Nanostructures

    Controlling thermal energy transfer at the nanoscale and thermal properties has become critically important in many applications since it often limits device performance. In this study, the effects on thermal conductivity arising from the nanoscale structure of free-standing nanocrystalline silicon films and the increasing surface-to-volume ratio when fabricated into suspended optomechanical nanobeams are studied. Thermal transport and elucidate the relative impact of different grain size distributions and geometrical dimensions on thermal conductivity are characterized. A micro time-domain thermoreflectance method to study free-standing nanocrystalline silicon films and find a drastic reduction in the thermal conductivity, down to values below 10 W m–1 K–1 is used, with a stronger decrease for smaller grains. In optomechanical nanostructures, this effect is smaller than in membranes due to the competition of surface scattering in decreasing thermal conductivity. Finally, a novel versatile contactless characterization technique that can be adapted to any structure supporting a thermally shifted optical resonance is introduced. The thermal conductivity data agrees quantitatively with the thermoreflectance measurements. This study opens the way to a more generalized thermal characterization of optomechanical cavities and to create hot-spots with engineered shapes at the desired position in the structures as a means to study thermal transport in coupled photon-phonon structures. © 2021 The Authors. Advanced Functional Materials published by Wiley-VCH GmbH

  • Thermal transport in silver-coated polymer sphere composites by the bidirectional 3 ω method

    Sandell S., Wang T., Chávez-Ángel E., Kristiansen H., Zhang Z., He J. Journal of Applied Physics; 131 (12, 125107) 2022. 10.1063/5.0080682. IF: 2.546

    Phononic and Photonic Nanostructures

    The bidirectional 3 ω method is an electrothermal technique that is commonly used to obtain the thermal conductivity of materials such as liquids, biological samples, and pastes. In this work, an epoxy-based adhesive was filled with monodisperse 10 μm polymethyl methacrylate spheres coated with silver thin films (AgPS), such that a metallic network that dominated the thermal transport was formed through the composite. The bidirectional 3 ω method was used to obtain the thermal conductivity of the conductive adhesive at different volume fractions of AgPS. For 50 vol.% AgPS, corresponding to 3.4 vol.% silver, the thermal conductivity was 2.03 ± 0.21 W m-1 K-1. The results show that the thermal conductivity is strongly correlated with the AgPS volume fraction, while maintaining a volume fraction of silver far below the commercial silver paste, which has typical filler fractions of 40 vol.% silver. The results of this work were compared to thermal measurements of the same material by other techniques, and advantages and disadvantages of the methods were finally discussed. © 2022 Author(s).

  • Toward Optimized Charge Transport in Multilayer Reduced Graphene Oxides

    Çlnar M.N., Antidormi A., Nguyen V.-H., Kovtun A., Lara-Avila S., Liscio A., Charlier J.-C., Roche S., Sevinçli H. Nano Letters; 22 (6): 2202 - 2208. 2022. 10.1021/acs.nanolett.1c03883. IF: 11.189

    Theoretical and Computational Nanoscience

    In the context of graphene-based composite applications, a complete understanding of charge conduction in multilayer reduced graphene oxides (rGO) is highly desirable. However, these rGO compounds are characterized by multiple and different sources of disorder depending on the chemical method used for their synthesis. Most importantly, the precise role of interlayer interaction in promoting or jeopardizing electronic flow remains unclear. Here, thanks to the development of a multiscale computational approach combining first-principles calculations with large-scale transport simulations, the transport scaling laws in multilayer rGO are unraveled, explaining why diffusion worsens with increasing film thickness. In contrast, contacted films are found to exhibit an opposite trend when the mean free path becomes shorter than the channel length, since conduction becomes predominantly driven by interlayer hopping. These predictions are favorably compared with experimental data and open a road toward the optimization of graphene-based composites with improved electrical conduction. © 2022 American Chemical Society. All rights reserved.

  • Tunable Thermofluorochromic Sensors Based on Conjugated Polymers

    Bellacanzone C., Otaegui J.R., Hernando J., Ruiz-Molina D., Roscini C. Advanced Optical Materials; 2022. 10.1002/adom.202102423. IF: 9.926

    Nanostructured Functional Materials

    Even though thermofluorochromic materials are eternal candidates for their use in multiple applications, they are still limited as they require complex synthetic strategies to accomplish tunable optical properties and/or provide optical changes only over a very wide temperature range. By taking advantage of the high sensitivity of the optical properties of conjugated polymers and oligomers to the external environment, herein phase change material (PCM)-based thermofluorochromic mixtures are created, where the solid-to-liquid transition of the PCM host triggers a sharp fluorescence color change of the dispersed polymers/oligomers. Fluorophore conjugation length, concentration, and PCM nature can be used to vary the spectral properties of the resulting materials along the visible region, covering a large part of the CIE 1931 color space. For the preparation of functional devices, this behavior can be directly transferred to the solid state by soaking or printing cellulose papers with the obtained thermofluorochromic mixtures as well as by structuring them into solid lipid particles that can be dispersed within polymer matrices. The resulting materials show very promising features as thermal sensors and anticounterfeiting labels. © 2022 The Authors. Advanced Optical Materials published by Wiley-VCH GmbH.

  • Ultralarge Free-Standing Imine-Based Covalent Organic Framework Membranes Fabricated via Compression

    Martín-Illán J.Á., Suárez J.A., Gómez-Herrero J., Ares P., Gallego-Fuente D., Cheng Y., Zhao D., Maspoch D., Zamora F. Advanced Science; 9 (7, 2104643) 2022. 10.1002/advs.202104643. IF: 16.806

    Supramolecular NanoChemistry and Materials

    Demand continues for processing methods to shape covalent organic frameworks (COFs) into macroscopic objects that are needed for their practical applications. Herein, a simple compression method to prepare large-scale, free-standing homogeneous and porous imine-based COF-membranes with dimensions in the centimeter range and excellent mechanical properties is reported. This method entails the compression of imine-based COF-aerogels, which undergo a morphological change from an elastic to plastic material. The COF-membranes fabricated upon compression show good performances for the separation of gas mixtures of industrial interest, N2/CO2 and CH4/CO2. It is believed that the new procedure paves the way to a broader range of COF-membranes. © 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.

  • Ultrastable glasses: new perspectives for an old problem

    Rodriguez-Tinoco C., Gonzalez-Silveira M., Ramos M.A., Rodriguez-Viejo J. Rivista del Nuovo Cimento; 2022. 10.1007/s40766-022-00029-y. IF: 3.000

    Thermal Properties of Nanoscale Materials

    Ultrastable glasses (mostly prepared from the vapor phase under optimized deposition conditions) represent a unique class of materials with low enthalpies and high kinetic stabilities. These highly stable and dense glasses show unique physicochemical properties, such as high thermal stability, improved mechanical properties or anomalous transitions into the supercooled liquid, offering unprecedented opportunities to understand many aspects of the glassy state. Their improved properties with respect to liquid-cooled glasses also open new prospects to their use in applications where liquid-cooled glasses failed or where not considered as usable materials. In this review article we summarize the state of the art of vapor-deposited (and other) ultrastable glasses with a focus on the mechanism of equilibration, the transformation to the liquid state and the low temperature properties. The review contains information on organic, metallic, polymeric and chalcogenide glasses and an updated list with relevant properties of all materials known today to form a stable glass. © 2022, The Author(s).

  • Unraveling Heat Transport and Dissipation in Suspended MoSe2 from Bulk to Monolayer

    Saleta Reig D., Varghese S., Farris R., Block A., Mehew J.D., Hellman O., Woźniak P., Sledzinska M., El Sachat A., Chávez-Ángel E., Valenzuela S.O., van Hulst N.F., Ordejón P., Zanolli Z., Sotomayor Torres C.M., Verstraete M.J., Tielrooij K.-J. Advanced Materials; 34 (10, 2108352) 2022. 10.1002/adma.202108352. IF: 30.849

    Ultrafast Dynamics in Nanoscale Systems | Theory and Simulation | Physics and Engineering of Nanodevices | Phononic and Photonic Nanostructures

    Understanding heat flow in layered transition metal dichalcogenide (TMD) crystals is crucial for applications exploiting these materials. Despite significant efforts, several basic thermal transport properties of TMDs are currently not well understood, in particular how transport is affected by material thickness and the material's environment. This combined experimental–theoretical study establishes a unifying physical picture of the intrinsic lattice thermal conductivity of the representative TMD MoSe2. Thermal conductivity measurements using Raman thermometry on a large set of clean, crystalline, suspended crystals with systematically varied thickness are combined with ab initio simulations with phonons at finite temperature. The results show that phonon dispersions and lifetimes change strongly with thickness, yet the thinnest TMD films exhibit an in-plane thermal conductivity that is only marginally smaller than that of bulk crystals. This is the result of compensating phonon contributions, in particular heat-carrying modes around ≈0.1 THz in (sub)nanometer thin films, with a surprisingly long mean free path of several micrometers. This behavior arises directly from the layered nature of the material. Furthermore, out-of-plane heat dissipation to air molecules is remarkably efficient, in particular for the thinnest crystals, increasing the apparent thermal conductivity of monolayer MoSe2 by an order of magnitude. These results are crucial for the design of (flexible) TMD-based (opto-)electronic applications. © 2022 The Authors. Advanced Materials published by Wiley-VCH GmbH

  • Voltage control of magnetism with magneto-ionic approaches: Beyond voltage-driven oxygen ion migration

    De Rojas J., Quintana A., Rius G., Stefani C., Domingo N., Costa-Krämer J.L., Menéndez E., Sort J. Applied Physics Letters; 120 (7, 070501) 2022. 10.1063/5.0079762. IF: 3.791

    Oxide Nanophysics

    Magneto-ionics is an emerging field in materials science where voltage is used as an energy-efficient means to tune magnetic properties, such as magnetization, coercive field, or exchange bias, by voltage-driven ion transport. We first discuss the emergence of magneto-ionics in the last decade, its core aspects, and key avenues of research. We also highlight recent progress in materials and approaches made during the past few years. We then focus on the "structural-ion"approach as developed in our research group in which the mobile ions are already present in the target material and discuss its potential advantages and challenges. Particular emphasis is given to the energetic and structural benefits of using nitrogen as the mobile ion, as well as on the unique manner in which ionic motion occurs in CoN and FeN systems. Extensions into patterned systems and textures to generate imprinted magnetic structures are also presented. Finally, we comment on the prospects and future directions of magneto-ionics and its potential for practical realizations in emerging fields, such as neuromorphic computing, magnetic random-access memory, or micro- and nano-electromechanical systems. © 2022 Author(s).

  • Wearable and fully printed microfluidic nanosensor for sweat rate, conductivity, and copper detection with healthcare applications

    Yang Q., Rosati G., Abarintos V., Aroca M.A., Osma J.F., Merkoçi A. Biosensors and Bioelectronics; 202 (114005) 2022. 10.1016/j.bios.2022.114005. IF: 10.618

    Nanobioelectronics and Biosensors

    Wearables are becoming pervasive in our society, but they are still mainly based on physical sensors with just few optical and electrochemical exceptions. Sweat, amongst other body fluids, is easily and non-invasively accessible, abundant, and relatively poor of interfering species. The biomarkers of interest in sweat space from ions and small molecules to whole organisms. Heavy metals have been found being biomarkers of several diseases and pathological conditions. Copper in particular is correlated to Wilson's disease and liver cirrhosis among others. Nevertheless, several issues such as sampling conditions, sweat rate normalization, reliable continuous monitoring, and typically expensive fabrication methods still needs to be addressed in sweat analysis with wearables. Herein, we propose a fully printed wearable microfluidic nanosensor with an integrated wireless smartphone-based readout. Our system can easily be applied on the skin and actively stimulate perspiration, normalizing the heavy metals concentration with respect to the volume of the sample and the sweat rate. The system has a limit of detection of 396 ppb, a linear range up to 2500 ppb and a sensitivity of 2.3 nA/ppb. © 2022