Publications
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Can polyoxometalates enhance the capacitance and energy density of activated carbon in organic electrolyte supercapacitors?
Zhu J.-J., Benages-Vilau R., Gomez-Romero P. Electrochimica Acta; 362 (137007) 2020. 10.1016/j.electacta.2020.137007. IF: 6.215
Polyoxometalates (POMs) have been shown to work as faradaic additives to activated carbon (AC) in acidic aqueous electrolytes. Yet, their use in organic media allows not only for added capacity but also higher voltage. Here we show that the tetraethylammonium derivative of phosphotungstate [PW12O40]3− (PW12) can be homogeneously distributed throughout the pores of activated carbon (AC) in organic solvents such as N,N’-dimethylformamide (DMF) and demonstrate the use of this hybrid electrode material in an organic electrolyte (1 M TEABF4 in acetonitrile) supercapacitor. Our results show the efficient electroactivity of the PW12 cluster even in the absence of protons, providing a higher voltage than aqueous electrolytes and fast and reversible redox activity. The hybrid material shows a combination of double-layer (AC) and redox (PW12) capacities leading to an increase (36%) in volumetric capacitance with respect to pristine AC in the same organic electrolyte (1 M TEABF4 in acetonitrile). Remarkably, we were able to quantify this increase as coming predominantly from non-diffusion-limited processes thanks to the utterly dispersed nature of POMs. Moreover, the hybrid material delivers a good rate capability and excellent cycle stability (93% retention of the initial capacitance after 10,000 cycles). This study has a profound significance on improving capacitance of carbon-based materials in organic electrolytes. © 2020 Elsevier Ltd
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Dual carbon potassium-ion capacitors: Biomass-derived graphenelike carbon nanosheet cathodes
Dubal D.P., Pham H.D., Mahale K., Hoang T.M.L., Mundree S.G., Gomez-Romero P. ACS Applied Materials and Interfaces; 12 (43): 48518 - 48525. 2020. 10.1021/acsami.0c12379. IF: 8.758
Potassium-ion storage devices are attracting tremendous attention for wide-ranging applications on account of their low cost, fast charge transport in electrolytes, and large working voltage. However, developing cost-effective, high-energy electrodes with excellent structural stability to ensure long-term cycling performance is a major challenge. In this contribution, we have derived two different forms of carbon materials from almond shells using different chemical treatments. For instance, hard carbon (HC) and graphene-like activated carbon (AC) nanosheets are developed by employing simple carbonization and chemical activation routes, respectively. The resultant hard carbon (AS-HC) and activated carbon (AS-AC) exhibit outstanding electrochemical performance as negative and positive electrodes in a potassium-ion battery (KIB), respectively, through their tailor-made surface properties. These promising benefits pave a way to construct a biomass-derived carbon potassium-ion capacitor (KIC) by employing AS-HC as the negative electrode and AS-AC as the positive electrode in a K-based electrolyte. The as-fabricated KIC delivers a reasonable specific energy of 105 Wh/kg and excellent cycling life with negligible capacitance fading over 10 000 cycles. This "waste-to-wealth"approach can promote the development of sustainable KICs at low cost and inspire their use for fastrate K-based energy storage applications. © 2020 American Chemical Society.
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Enhancement of organophosphate degradation by electroactive pyrrole and imidazole copolymers
Hryniewicz B.M., Wolfart F., Gómez-Romero P., Orth E.S., Vidotti M. Electrochimica Acta; 338 (135842) 2020. 10.1016/j.electacta.2020.135842. IF: 6.215
Many chemical warfare agents and agrochemicals are composed by organophosphates, that present high toxicity and difficult spontaneous degradation. Amongst the different catalysts to degrade these compounds, heterogeneous systems stand out since they provide easy recovery of the catalyst. However, the limited diffusion of the substrate decreases the rate of the reactions when compared to homogeneous catalysis. To reach a good efficiency in the dephosphorylation, we created heterogeneous catalysts based on pyrrole and imidazole that can enhance the degradation by different effects; both catalytic activity of imidazole and electroactivity of polypyrrole were evaluated. Spectroelectrochemical studies evidenced that the rate constant changes with the applied potential, indicating different reaction mechanisms with the material in the oxidized and neutral states. In summary, a new perspective allying conducting polymers with chemical catalysts was explored. This cooperative effect should be considered in future works concerning the search for new materials to monitor and eliminate organophosphates. © 2020 Elsevier Ltd
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Fabrication of 3D binder-free graphene NiO electrode for highly stable supercapattery
Agudosi E.S., Abdullah E.C., Numan A., Mubarak N.M., Aid S.R., Benages-Vilau R., Gómez-Romero P., Khalid M., Omar N. Scientific Reports; 10 (1, 11214) 2020. 10.1038/s41598-020-68067-2. IF: 3.998
Electrochemical stability of energy storage devices is one of their major concerns. Polymeric binders are generally used to enhance the stability of the electrode, but the electrochemical performance of the device is compromised due to the poor conductivity of the binders. Herein, 3D binder-free electrode based on nickel oxide deposited on graphene (G-NiO) was fabricated by a simple two-step method. First, graphene was deposited on nickel foam via atmospheric pressure chemical vapour deposition followed by electrodeposition of NiO. The structural and morphological analyses of the fabricated G-NiO electrode were conducted through Raman spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray spectroscopy (EDS). XRD and Raman results confirmed the successful growth of high-quality graphene on nickel foam. FESEM images revealed the sheet and urchin-like morphology of the graphene and NiO, respectively. The electrochemical performance of the fabricated electrode was evaluated through cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) in aqueous solution at room temperature. The G-NiO binder-free electrode exhibited a specific capacity of ≈ 243 C g−1 at 3 mV s−1 in a three-electrode cell. A two-electrode configuration of G-NiO//activated charcoal was fabricated to form a hybrid device (supercapattery) that operated in a stable potential window of 1.4 V. The energy density and power density of the asymmetric device measured at a current density of 0.2 A g−1 were estimated to be 47.3 W h kg−1 and 140 W kg−1, respectively. Additionally, the fabricated supercapattery showed high cyclic stability with 98.7% retention of specific capacity after 5,000 cycles. Thus, the proposed fabrication technique is highly suitable for large scale production of highly stable and binder-free electrodes for electrochemical energy storage devices. © 2020, The Author(s).
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Graphene triggered enhancement in visible-light active photocatalysis as well as in energy storage capacity of (CFO)1-x(GNPs)x nanocomposites
Israr M., Iqbal J., Arshad A., Rani M., Gómez‐Romero P., Benages R. Ceramics International; 46 (3): 2630 - 2639. 2020. 10.1016/j.ceramint.2019.09.232. IF: 3.830
Cobalt ferrite-graphene nanoplatelets ((CFO)1-x(GNPs)x) nanocomposites are promising for efficient photocatalysis and high-performance supercapacitors. Multifunctional (CFO)1-x(GNPs)x nanocomposites prepared via facile chemical method have been investigated for their physio-chemical characteristics like crystal structure, morphology, chemical composition, optical properties, infrared vibrational modes, photocatalytic and supercapacitor applications. Interestingly, the photocatalytic activity of CFO nanostructures has been improved significantly from 38.3% to 98.7% with the addition of graphene which can be attributed to control over recombination of charge carriers. It is also found that the specific capacitance of the prepared (CFO)1-x(GNPs)x nanocomposite electrode at 0.5 Ag-1 is three times higher than that of only CFO based electrode which could be due to the conducting nature of graphene nanoplatelets (GNPs). The enhanced photocatalytic and improved electrochemical characteristics suggest the effective use of prepared nanocomposites in water purification and supercapacitor nanodevices. © 2019 Elsevier Ltd and Techna Group S.r.l.
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Highly Loaded Mildly Edge-Oxidized Graphene Nanosheet Dispersions for Large-Scale Inkjet Printing of Electrochemical Sensors
Nagar B., Jović M., Bassetto V.C., Zhu Y., Pick H., Gómez-Romero P., Merkoçi A., Girault H.H., Lesch A. ChemElectroChem; 7 (2): 460 - 468. 2020. 10.1002/celc.201901697. IF: 4.154
Inkjet printing of electrochemical sensors using a highly loaded mildly edge-oxidized graphene nanosheet (EOGN) ink is presented. An ink with 30 mg/mL EOGNs is formulated in a mixture of N-methyl pyrrolidone and propylene glycol with only 30 min of sonication. The absence of additives, such as polymeric stabilizers or surfactants, circumvents reduced electrochemical activity of coated particles and avoids harsh post-printing conditions for additive removal. A single light pulse from a xenon flash lamp dries the printed EGON film within a fraction of a second and creates a compact electrode surface. An accurate coverage with only 30.4 μg of EOGNs per printed layer and cm2 is achieved. The EOGN films adhere well to flexible polyimide substrates in aqueous solution. Electrochemical measurements were performed using cyclic voltammetry and differential pulse voltammetry. An all inkjet-printed three-electrode living bacterial cell detector is prepared with EOGN working and counter electrodes and silver-based quasi-reference electrode. The presence of E. coli in liquid samples is recorded with four electroactive metabolic activity indicators. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Multifunctional MgFe2O4/GNPs nanocomposite: Graphene-promoted visible light driven photocatalytic activity and electrochemical performance of MgFe2O4 nanoparticles
Israr M., Iqbal J., Arshad A., Gómez‐Romero P., Benages R. Solid State Sciences; 110 (106363) 2020. 10.1016/j.solidstatesciences.2020.106363. IF: 2.434
Herein, the electrochemical and photodegradation properties of magnesium ferrite and graphene-nanoplatelets nanocomposites, (MFO)1-x(GNPs)x, (x = 0.25, 0.50, 0.75) are reported. Benefitting from the effective interfacial interaction of the bi-phase nanocomposite and superior electrical conduction of GNPs, a significant enhancement in supercapacitive performance has been demonstrated. Interestingly, the electrochemical properties of nanocomposite electrode were found to depend on the loading ratio of GNPs. Notably the (MFO)0.50(GNPs)0.50 (50 wt % GNPs) shows an outstanding energy storage capacity i.e., 612 Fg–1 at 0.5 Ag–1 with 21.25 Wh kg−1 energy density at power density of 125 W kg−1 and retains ~76.8 % of the first cycle capacitance after continuous 1500 charge/discharge cycles. Furthermore, the (MFO)0.75(GNPs)0.25 (25 wt % GNPs) composite demonstrates admirable photodegradation efficiency (99.3 % in 60 min of visible light illumination) which is 3.2 times than that of neat MFO nanoparticles. The superior electrochemical and photodegradation performance suggests that the prepared nanocomposites can be effectively utilized in high‐performance energy storage devices and low cost, eco-friendly water purification systems. © 2020 Elsevier Masson SAS
