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Zou, Yiming, Ronn Goei, Su-Ann Ong, Amanda Jiamin ONG, Jingfeng Huang i Alfred Iing Yoong TOK. "Development of Core-Shell Rh@Pt and Rh@Ir Nanoparticle Thin Film Using Atomic Layer Deposition for HER Electrocatalysis Applications". Processes 10, nr 5 (18.05.2022): 1008. http://dx.doi.org/10.3390/pr10051008.
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The efficiency of hydrogen gas generation via electrochemical water splitting has been mostly limited by the availability of electrocatalyst materials that require lower overpotentials during the redox reaction. Noble metals have been used extensively as electrocatalysts due to their high activity and low overpotentials. However, the use of single noble metal electrocatalyst is limited due to atomic aggregation caused by its inherent high surface energy, which results in poor structural stability, and, hence, poor electrocatalytic performance and long-term stability. In addition, using noble metals as electrocatalysts also causes the cost to be unnecessarily high. These limitations in noble metal electrocatalysts could be enhanced by combining two noble metals in a core-shell structure (e.g., Rh@Ir) as a thin film over a base substrate. This could significantly enhance electrocatalytic activity due to the following: (1) the modification of the electronic structure, which increases electrical conductivity; (2) the optimization of the adsorption energy; and (3) the introduction of new active sites in the core-shell noble metal structure. The current state-of-the-art employs physical vapor deposition (PVD) or other deposition techniques to fabricate core-shell noble metals on flat 2D substrates. This method does not allow 3D substrates with high surface areas to be used. In the present work, atomic layer deposition (ALD) was used to fabricate nanoparticle thin films of Rh@Ir and Rh@Pt in a core-shell structure on glassy carbon electrodes. ALD enables the fabrication of nanoparticle thin film on three-dimensional substrates (a 2D functional film on a 3D substrate), resulting in a significantly increased surface area for a catalytic reaction to take place; hence, improving the performance of electrocatalysis. The Rh@Pt (with an overpotential of 139 mV and a Tafel slope of 84.8 mV/dec) and Rh@Ir (with an overpotential of 169 mV and a Tafel slope of 112 mV/dec) core-shell electrocatalyst exhibited a better electrocatalytic performances compared to the single metal Rh electrocatalyst (with an overpotential of 300 mV and a Tafel slope of 190 mV/dec). These represented a 54% and a 44% improvement in performance, respectively, illustrating the advantages of core-shell thin film nanostructures in enhancing the catalytic performance of an electrocatalyst. Both electrocatalysts also exhibited good long-term stability in the harsh acidic electrolyte conditions when subjected to chronopotentiometry studies.
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Weng, Yu-Ching, Cheng-Jen Ho, Hui-Hsuan Chiao i Chen-Hao Wang. "Pt3Ni/C and Pt3Co/C cathodes as electrocatalysts for use in oxygen sensors and proton exchange membrane fuel cells". Zeitschrift für Naturforschung B 75, nr 12 (16.12.2020): 1029–35. http://dx.doi.org/10.1515/znb-2020-0116.
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AbstractThe composites Pt3Ni/C and Pt3Co/C are electrocatalysts for oxygen reduction reactions (ORRs). This study compares the electrocatalytic activity of these electrodes that are used to detect oxygen, and determines their suitability for use in proton exchange membrane fuel cells (PEMFCs). Chemical reduction is used to produce the Pt3Ni/C and Pt3Co/C electrocatalysts. The particle size, elemental composition and crystallinity of the intermetallic electrocatalysts are determined using transmission electron microscopy (TEM) and an energy-dispersive spectrometer (EDX). The ORR activity of the Pt3Ni/C and Pt3Co/C electrocatalysts is determined using cyclic voltammetry (CV), a polarization curve (PC) and a rotating disk electrode (RDE). The Pt3Ni/C electrode registers a greater current for the ORR as compared to the Pt3Co/C electrode. Both electrodes exhibit a linear relationship between response current and oxygen concentration in the detection range from 100 to 1000 ppm. The Pt3Ni/C electrode exhibits a significant sensitivity to oxygen up to 13.4 μA ppm−1 cm−2. A membrane electrode assembly (MEA) that is produced using Pt3Ni/C as a cathodic electrocatalyst in a single PEMFC generates a maximum power density of 1097 mW cm−2.
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Kudur Jayaprakash, Gururaj, B. E. Kumara Swamy, Roberto Flores-Moreno i Kayim Pineda-Urbina. "Theoretical and Cyclic Voltammetric Analysis of Asparagine and Glutamine Electrocatalytic Activities for Dopamine Sensing Applications". Catalysts 13, nr 1 (3.01.2023): 100. http://dx.doi.org/10.3390/catal13010100.
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The molecular dynamics and density functional theory (DFT) can be applied to discriminate electrocatalyst’s electron transfer (ET) properties. It will be interesting to discriminate the ET properties of green electrocatalysts such as amino acids. Here, we have used DFT to compare the electrocatalytic abilities of asparagine and glutamine at the carbon paste electrode interface. Cyclic voltammetric results reveal that the electrocatalytic activities of aspargine are higher than glutamine for dopamine sensing. Dopamine requires less energy to bind with asparagine when compared to glutamine. Additionally, asparagine has higher electron-donating and accepting powers. Therefore, asparagine has a higher electrocatalytic activity than glutamine—the ability for the asparagine and glutamine carbon electrodes to detect dopamine in commercial injection, and to obtain satisfactory results. As a part of the work, we have also studied dopamine interaction with the modified carbon surface using molecular dynamics.
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Xu, Zhiying, Minghui Hao, Xin Liu, Jingjing Ma, Liang Wang, Chunhu Li i Wentai Wang. "Co(OH)2 Nanoflowers Decorated α-NiMoO4 Nanowires as a Bifunctional Electrocatalyst for Efficient Overall Water Splitting". Catalysts 12, nr 11 (11.11.2022): 1417. http://dx.doi.org/10.3390/catal12111417.
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The development of bifunctional electrocatalysts with high catalytic activity and cyclic stability is an effective method for electrocatalytic water splitting. Herein, a promising hydroxide/oxide Co(OH)2/α-NiMoO4 NWs/CC heterostructure with nanoflowers decorating the nanowires was fabricated on a carbon cloth (CC) substrate via hydrothermal and calcination methods. In contrast to one-dimensional nanomaterials, the interfaces of Co(OH)2 nanoflowers and α-NiMoO4 nanowires on CC provide more active sites for electrocatalytic reactions; therefore, they exhibit obviously enhanced electrocatalytic activities in overall water splitting. Specifically, the Co(OH)2/α-NiMoO4 NWs/CC electrodes exhibit an overpotential of 183.01 mV for hydrogen evolution reaction (HER) and of 170.26 mV for oxygen evolution reactions (OER) at the current density of 10 mA cm−2 in 1.0 M KOH. Moreover, the electrocatalytic oxygen evolution reaction (OER) activity of the Co(OH)2/α-NiMoO4 NWs/CC electrocatalyst was enhanced after long-term stability tests.
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Tang, Chaoyun, Tewodros Asefa i Nianqiang Wu. "Metal-Coordinated Hydrogels As Efficient Oxygen Evolution Electrocatalysts". ECS Meeting Abstracts MA2022-02, nr 48 (9.10.2022): 1798. http://dx.doi.org/10.1149/ma2022-02481798mtgabs.
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Conductive polymer hydrogels have large surface area and high conductivity. Their properties can easily be tailored further by functionalizing them with metals and nonmetals. However, the potential of metal-conjugated hydrogels for electrocatalysis has rarely been investigated. In this work, we report the synthesis of transition metals-conjugated polyaniline-phytic acid (PANI-PA) hydrogels that show efficient electrocatalytic properties for the oxygen evolution reaction (OER). Among many transition metals studied, Fe is accommodated by the hydrogel the most because of the favorable affinity of the PA groups in the hydrogel for Fe. Meanwhile, those containing both Fe and Co are found to be the most effective for electrocatalysis of OER. The most optimized such hydrogel, NF@Hgel-Fe0.3Co0.1, which has 3:1 ratio of Fe and Co, needs an overpotential of only 280 mV to catalyze OER with a current density of 10 mV cm-2 in 1 M KOH solution. Furthermore, these metal-doped PANI-PA hydrogels can easily be loaded on nickel foam and carbon cloth via a simple soak-and-dry method to form free-standing electrodes. Overall, the work demonstrates a facile synthesis and fabrication of sustainable OER electrocatalysts and electrodes that are composed of easily processable hydrogels conjugated with various earth-abundant transition metals. Figure R. Schematic illustration of the synthesis of PA-PANI-Metal (Hgel-M x ) hydrogels for electrocatalysis of OER. Figure 1
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Balint, Lorena-Cristina, Iosif Hulka i Andrea Kellenberger. "Pencil Graphite Electrodes Decorated with Platinum Nanoparticles as Efficient Electrocatalysts for Hydrogen Evolution Reaction". Materials 15, nr 1 (23.12.2021): 73. http://dx.doi.org/10.3390/ma15010073.
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Platinum-based materials are widely known as the most utilized and advanced catalysts for hydrogen evolution reaction. For this reason, several studies have reported alternative methods of incorporating this metal into more economical electrodes with a carbon-based support material. Herein, we report on the performance of pencil graphite electrodes decorated with electrochemically deposited platinum nanoparticles as efficient electrocatalysts for hydrogen evolution reaction. The electrodeposition of platinum was performed via pulsed current electrodeposition and the effect of current density on the electrocatalytic activity was investigated. The obtained electrodes were characterized using cyclic voltammetry, while the electrocatalytic activity was assessed through linear sweep voltammetry. Field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy were utilised to gain an insight into surface morphology and chemical analysis of platinum nanoparticles. The best performing electrocatalyst, at both low and high current densities, was characterized by the highest exchange current density of 1.98 mA cm−2 and an ultralow overpotential of 43 mV at a current density of 10 mA cm−2. The results show that, at low current densities, performances closest to that of platinum can be achieved even with an ultralow loading of 50 µg cm−2 Pt.
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Kim, Sang Kyum, Ji Yun Park, Soon Choel Hwang, Do Kyun Lee, Sang Heon Lee, Moon Hee Han i Young Woo Rhee. "Radiolytic Preparation of Electrocatalysts with Pt-Co and Pt-Sn Nanoparticles for a Proton Exchange Membrane Fuel Cell". Journal of Nanomaterials 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/960379.
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Nanosized Pt-Sn/VC and Pt-Co/VC electrocatalysts were prepared by a one-step radiation-induced reduction (30 kGy) process using distilled water as the solvent and Vulcan XC72 as the supporting material. While the Pt-Co/VC electrodes were compared with Pt/VC (40 wt%, HiSpec 4000), in terms of their electrocatalytic activity towards the oxidation of H2, the Pt-Co/VC electrodes were evaluated in terms of their activity towards the hydrogen oxidation reaction (HOR) and compared with Pt/VC (40 wt%, HiSpec 4000), Pt-Co/VC, and Pt-Sn/VC in a single cell. Additionally, the prepared electrocatalyst samples (Pt-Co/VC and Pt-Sn/VC) were characterized by transmission electron microscopy (TEM), scanning electron microscope (SEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electrochemical surface area (ECSA), and fuel cell polarization performance.
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Owhoso, Fiki V., i David G. Kwabi. "Effect of Covalent Modification on Proton-Coupled Electron Transfer at Quinone-Functionalized Carbon Electrodes". ECS Meeting Abstracts MA2022-02, nr 57 (9.10.2022): 2171. http://dx.doi.org/10.1149/ma2022-02572171mtgabs.
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Electrodes functionalized with molecularly well-defined reactive/catalytic species have become attractive for promoting a wide variety of electrochemical energy conversion processes or systems, such as electrocatalytic CO2 and O2 reduction, as well as metal-sulfur and redox-flow batteries.1-3 Critical to the performance of these electrodes is the interaction between the electric field, and the molecular species at the electrical double layer. Nevertheless, elucidating the potential/electric field experienced at the functionalized interface is challenging. We show in this work that the acid-base thermochemical (i.e. Pourbaix) behavior of molecular quinones can vary depending on their mode of covalent attachment to a carbon electrode and ionic strength of the electrolyte, in a manner that sheds light on the experienced interfacial electric field. This work can inform strategies for effective pH modulation at electrified interfaces in ways that can enhance the electrocatalytic processes and systems mentioned above, and enable newer applications such as pH-swing-based electrochemical CO2 capture using appropriately chemically modified electrodes.4 References 1 Ren, G. et al. Porous Core–Shell Fe3C Embedded N-doped Carbon Nanofibers as an Effective Electrocatalysts for Oxygen Reduction Reaction. ACS Applied Materials & Interfaces 8, 4118-4125, doi:10.1021/acsami.5b11786 (2016). 2 Zhang, S., Fan, Q., Xia, R. & Meyer, T. J. CO2 Reduction: From Homogeneous to Heterogeneous Electrocatalysis. Accounts of Chemical Research 53, 255-264, doi:10.1021/acs.accounts.9b00496 (2020). 3 Zhao, C.-X. et al. Semi-Immobilized Molecular Electrocatalysts for High-Performance Lithium–Sulfur Batteries. Journal of the American Chemical Society 143, 19865-19872, doi:10.1021/jacs.1c09107 (2021). 4 Jin, S., Wu, M., Gordon, R. G., Aziz, M. J. & Kwabi, D. G. pH swing cycle for CO2 capture electrochemically driven through proton-coupled electron transfer. Energy & Environmental Science, doi:10.1039/D0EE01834A (2020).
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Díaz-Sainz, Guillermo, Manuel Alvarez-Guerra i Angel Irabien. "Continuous Electrochemical Reduction of CO2 to Formate: Comparative Study of the Influence of the Electrode Configuration with Sn and Bi-Based Electrocatalysts". Molecules 25, nr 19 (28.09.2020): 4457. http://dx.doi.org/10.3390/molecules25194457.
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Climate change has become one of the most important challenges in the 21st century, and the electroreduction of CO2 to value-added products has gained increasing importance in recent years. In this context, formic acid or formate are interesting products because they could be used as raw materials in several industries as well as promising fuels in fuel cells. Despite the great number of studies published in the field of the electrocatalytic reduction of CO2 to formic acid/formate working with electrocatalysts of different nature and electrode configurations, few of them are focused on the comparison of different electrocatalyst materials and electrode configurations. Therefore, this work aims at presenting a rigorous and comprehensive comparative assessment of different experimental data previously published after many years of research in different working electrode configurations and electrocatalysts in a continuous mode with a single pass of the inputs through the reactor. Thus, the behavior of the CO2 electroreduction to formate is compared operating with Sn and Bi-based materials under Gas Diffusion Electrodes (GDEs) and Catalyst Coated Membrane Electrodes (CCMEs) configurations. Considering the same electrocatalyst, the use of CCMEs improves the performance in terms of formate concentration and energy consumption. Nevertheless, higher formate rates can be achieved with GDEs because they allow operation at higher current densities of up to 300 mA·cm−2. Bi-based-GDEs outperformed Sn-GDEs in all the figures of merit considered. The comparison also highlights that in CCME configuration, the employ of Bi-based-electrodes enhanced the behavior of the process, increasing the formate concentration by 35% and the Faradaic efficiency by 11%.
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Garcia-Contreras, M. A., S. M. Fernandez-Valverde i J. R. Vargas-Garcia. "PtNi and CoNi Film Electrocatalysts Prepared by MOCVD for the Oxygen Reduction Reaction in Alkaline Media". Journal of New Materials for Electrochemical Systems 14, nr 2 (5.04.2011): 81–85. http://dx.doi.org/10.14447/jnmes.v14i2.114.
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CoNi and PtNi film electrocatalysts were prepared by Metal-Organic Chemical Vapour Deposition (MOCVD) and their electrocatalytic activity for the oxygen reduction reaction (ORR) in 0.5 M KOH was investigated by cyclic voltammetry and Rotating Disk Electrode techniques. Experiments included working electrodes of Co, Ni and Pt prepared also by MOCVD for comparison. The film electrocatalysts were characterized by X-ray diffraction, Scanning Electronic Microscopy and Energy dispersive X-ray analysis. Films thickness was about 200-250 nm and nanocrystallites were found in the range of 12 to 30 nm. In the same experimental conditions, the overpotential for the ORR at a current density of 1 mA cm-2 for PtNi film was 120 mV lower than the overpotential of Pt film electrocatalyst, and an enhanced activity was observed on PtNi with respect to Pt. The electrochemical response for the oxygen reduction reaction on CoNi film was higher than those of elemental Ni and Co films obtained by MOCVD. A good stability was obtained in a chronoamperometry test for the PtNi electrode, only affected by oxygen flow variations.
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Casado-Coterillo, Clara, Aitor Marcos-Madrazo, Aurora Garea i Ángel Irabien. "An Analysis of Research on Membrane-Coated Electrodes in the 2001–2019 Period: Potential Application to CO2 Capture and Utilization". Catalysts 10, nr 11 (22.10.2020): 1226. http://dx.doi.org/10.3390/catal10111226.
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The chemistry and electrochemistry basic fields have been active for the last two decades of the past century studying how the modification of the electrodes’ surface by coating with conductive thin films enhances their electrocatalytic activity and sensitivity. In light of the development of alternative sustainable ways of energy storage and carbon dioxide conversion by electrochemical reduction, these research studies are starting to jump into the 21st century to more applied fields such as chemical engineering, energy and environmental science, and engineering. The huge amount of literature on experimental works dealing with the development of CO2 electroreduction processes addresses electrocatalyst development and reactor configurations. Membranes can help with understanding and controlling the mass transport limitations of current electrodes as well as leading to novel reactor designs. The present work makes use of a bibliometric analysis directed to the papers published in the 21st century on membrane-coated electrodes and electrocatalysts to enhance the electrochemical reactor performance and their potential in the urgent issue of carbon dioxide capture and utilization.
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Owhoso, Fiki V., i David G. Kwabi. "Mapping the Double Layer Using Proton-Coupled Electron Transfer at Functionalized Carbon Electrodes". ECS Meeting Abstracts MA2022-01, nr 50 (7.07.2022): 2107. http://dx.doi.org/10.1149/ma2022-01502107mtgabs.
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Conductive electrodes functionalized with molecularly well-defined species are emerging as effective active materials for a wide range of applications, from electrocatalytic CO2 and O2 reduction, to high performance lithium-sulfur batteries.1–3 For redox-active species that participate in proton-coupled electron transfer (PCET), the extent of conjugation, applied potential, and distance between the redox center and electrode determine the potential and electric field experienced at the site of electron transfer. This electric field in turn determines the pH-dependent energetics of electron transfer (i.e. Pourbaix behavior) and the rate PCET. We discuss how measurements of PCET to redox-active species functionalized to carbon electrodes can yield insight into the potential and electric field profiles within the electrode-electrolyte double layer. Systematically increasing the distance between the redox-active moiety and the electrode results in the moiety experiencing a progressively weaker electric field, as determined by changes to PCET behavior. Based on these results, we propose strategies to quantify the strength of the electric field as a function of this distance. This work can inform strategies for effective pH modulation at electrified interfaces in ways that can enhance electrocatalytic processes and other applications, such as electrochemical CO2 capture based on pH swing. References Ren, G. et al. Porous Core-Shell Fe3C Embedded N-doped Carbon Nanofibers as an Effective Electrocatalysts for Oxygen Reduction Reaction. ACS Applied Materials and Interfaces 8, 4118–4125 (2016). Zhang, S., Fan, Q., Xia, R. & Meyer, T. J. CO2 Reduction: From Homogeneous to Heterogeneous Electrocatalysis. Accounts of Chemical Research 53, 255–264 (2020). Zhao, C.-X. et al. Semi-Immobilized Molecular Electrocatalysts for High-Performance Lithium–Sulfur Batteries. Journal of the American Chemical Society 143, 19865–19872 (2021).
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Hahn, Christopher, i Thomas F. Jaramillo. "Electrocatalysis for CO2 Reduction: Controlling Selectivity to Oxygenates and Multicarbon Products". ECS Meeting Abstracts MA2018-01, nr 31 (13.04.2018): 1832. http://dx.doi.org/10.1149/ma2018-01/31/1832.
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Many technical challenges remain for the implementation of CO2 electrolysis as a practical means for CO2 utilization. Here, we outline strategies for improving the performance of catalysts for the electroreduction of CO2 to oxygenated and multicarbon reduction products. To this end, we will first discuss how engineering the surface structure of Cu electrocatalysts led to the discovery of active site structure-selectivity relationships. Using a combination of electrocatalysis experiments and in situ surface probe microscopy, we demonstrate that undercoordinated sites are selective motifs for oxygenates and C-C coupling. By comparing these results with state-of-the-art Cu electrocatalysts from the literature, we show that different morphologies have similar intrinsic activities for CO2 reduction. Afterwards, we will discuss a tandem catalysis approach for improving upon these normalized CO2 reduction activities, which is enabled by utilizing bimetallic electrodes consisting of Au nanoparticles on polycrystalline Cu (Au/Cu). At low overpotentials, the Au/Cu electrocatalyst has a synergistic catalytic activity superior to that of either Cu or Au, indicating that tandem catalysis mechanisms can be utilized to increase the energy efficiency for alcohol production. By comparing Au/Cu to Cu, we highlight common potential-driven trends in the selectivity to oxygenated and multicarbon products, providing insights on how to develop new electrocatalysts that can guide selectivity to valuable chemicals and fuels.
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Seijas-Da Silva, Alvaro, Víctor Oestreicher, Eugenio Coronado i Gonzalo Abellán. "Influence of Fe-clustering on the water oxidation performance of two-dimensional layered double hydroxides". Dalton Transactions 51, nr 12 (2022): 4675–84. http://dx.doi.org/10.1039/d1dt03737d.
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The role of Fe-clustering on the OER performance of MgFe layered double hydroxides has been investigated. Low clustering improves the electrocatalysis using Ni foam electrodes, alerting about hidden electrode collector-electrocatalyst interactions.
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Banti, Angeliki, Kalliopi Maria Papazisi, Stella Balomenou i Dimitrios Tsiplakides. "Effect of Calcination Temperature on the Activity of Unsupported IrO2 Electrocatalysts for the Oxygen Evolution Reaction in Polymer Electrolyte Membrane Water Electrolyzers". Molecules 28, nr 15 (2.08.2023): 5827. http://dx.doi.org/10.3390/molecules28155827.
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Polymer electrolyte membrane (PEM) water electrolyzers suffer mainly from slow kinetics regarding the oxygen evolution reaction (OER). Noble metal oxides, like IrO2 and RuO2, are generally more active for OER than metal electrodes, exhibiting low anodic overpotentials and high catalytic activity. However, issues like electrocatalyst stability under continuous operation and cost minimization through a reduction in the catalyst loading are of great importance to the research community. In this study, unsupported IrO2 of various particle sizes (different calcination temperatures) were evaluated for the OER and as anode electrodes for PEM water electrolyzers. The electrocatalysts were synthesized by the modified Adams method, and the effect of calcination temperature on the properties of IrO2 electrocatalysts is investigated. Physicochemical characterization was conducted using X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area measurement, high-resolution transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) analyses. For the electrochemical performance of synthesized electrocatalysts in the OER, cyclic voltammetry (CV) and linear sweep voltammetry (LSV) were conducted in a typical three-cell electrode configuration, using glassy carbon as the working electrode, which the synthesized electrocatalysts were cast on in a 0.5 M H2SO4 solution. The materials, as anode PEM water electrolysis electrodes, were further evaluated in a typical electrolytic cell using a Nafion®115 membrane as the electrolyte and Pt/C as the cathode electrocatalyst. The IrO2 electrocatalyst calcined at 400 °C shows high crystallinity with a 1.24 nm particle size, a high specific surface area (185 m2 g−1), and a high activity of 177 mA cm−2 at 1.8 V for PEM water electrolysis.
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Shinde, Nanasaheb M., Siddheshwar D. Raut, Balaji G. Ghule, Ramesh J. Deokate, Sandesh H. Narwade, Rajaram S. Mane, Qixun Xia, James J. Pak i Jeom-Soo Kim. "Hydrogen Evolution Reaction Activities of Room-Temperature Self-Grown Glycerol-Assisted Nickel Chloride Nanostructures". Catalysts 13, nr 1 (12.01.2023): 177. http://dx.doi.org/10.3390/catal13010177.
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Three-dimensional nanomaterials of desired structural/morphological properties and highly porous with a high specific surface area are important in a variety of applications. In this work, glycerol-mediated self-growth of 3-D dandelion flower-like nickel chloride (NiCl2) from nickel-foam (NiF) is obtained for the first time using a room-temperature (27 °C) processed wet chemical method for electrocatalysis application. Glycerol-mediated self-grown NiCl2 flowers demonstrate an excellent electrocatalytic performance towards the hydrogen evolution reaction (HER), which is much superior to the NiF (303 mV) and NiCl2 electrode prepared without glycerol (208 mV) in the same electrolyte solution. With a Tafel slope of 41 mV dec−1, the NiCl2 flower electrode confirms improved reaction kinetics as compared to the other two electrodes, i.e., NiF (106 mVdec−1) and NiCl2 obtained without glycerol (56 mV dec−1). The stability of the glycerol-based NiCl2 electrode has further been carried out for 2000 cycles with the overpotential diminution of just 8 mV, approving an electrocatalyst potential of glycerol-based NiCl2 electrode towards HER kinetics. This simple and easy growth process involves nucleation, aggregation, and crystal growth steps for producing NiCl2 nanostructures for electrocatalytic water splitting application through the HER process.
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Tomczyk, Danuta, Wiktor Bukowski, Karol Bester i Michalina Kaczmarek. "Electrocatalytic Properties of Ni(II) Schiff Base Complex Polymer Films". Materials 15, nr 1 (28.12.2021): 191. http://dx.doi.org/10.3390/ma15010191.
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Platinum electrodes were modified with polymers of the (±)-trans-N,N′-bis(salicylidene)-1,2-cyclohexanediaminenickel(II) ([Ni(salcn)]) and (±)-trans-N,N′-bis(3,3′-tert-Bu-salicylidene)-1,2-cyclohexanediaminenickel(II) ([Ni(salcn(Bu))]) complexes to study their electrocatalytic and electroanalytical properties. Poly[Ni(salcn)] and poly[Ni(salcn(Bu))]) modified electrodes catalyze the oxidation of catechol, aspartic acid and NO2−. In the case of poly[Ni(salcn)] modified electrodes, the electrocatalysis process depends on the electroactive surface coverage. The films with low electroactive surface coverage are only a barrier in the path of the reducer to the electrode surface. The films with more electroactive surface coverage ensure both electrocatalysis inside the film and oxidation of the reducer directly on the electrode surface. In the films with the most electroactive surface coverage, electrocatalysis occurs only at the polymer–solution interface. The analysis was based on cyclic voltammetry, EQCM (electrochemical quartz crystal microbalance) and rotating disc electrode method.
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Ibrahim, Mohamed M., Gaber A. M. Mersal, Ahmed M. Fallatah, Rabah Boukherroub, Safaa N. Abdou i Mohammed A. Amin. "Electrochemical H2 Production using Polypyrazole based Zinc(II) Complex in Alkaline Medium". Asian Journal of Chemistry 34, nr 6 (2022): 1366–72. http://dx.doi.org/10.14233/ajchem.2022.23669.
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A zinc(II) complex of polypyazole containing ligand namely, [Tp*ZnCl] (Zn1) {Tp* = tris(3,5-dimethylpyrazolyl)borate}, along with its zinc(II) bound hydroxo complex [Tp*Zn–OH] (Zn2) were synthesized and characterized by FT-IR, Raman, 1H NMR techniques and elemental analysis. In alkaline solution (0.1 M KOH), the Zn2 modified glassy carbon (GC), namely GC–Zn2, was investigated as a molecular electrocatalyst for the hydrogen evolution reaction (HER). Different quantities (ca. 0.1–0.5 mg cm–2) of Zn2 were loaded on GC electrodes to make various GC–Zn2 electrodes. These electrodes were utilized as cathodes in 0.1 M KOH to produce H2 using linear sweep voltammetry (LSV) measurements. The HER electrocatalytic activity of the GC–Zn2 catalyst was found to be quite high and it increased with the catalyst loading density. The top performing electrocatalyst, GC–Zn2 (0.5 mg cm–2), demonstrated considerable HER catalytic performance with a low HER onset potential (EHER) of –33 mV vs. RHE and a high exchange current density of 0.59 mA cm–2. Moreover, the top performing electrocatalyst had a Tafel slope of –152 mV dec–1 and consumed an overpotential of 135 mV to generate a current density of 10 mA cm–2. Under the same operating conditions, these HER electrochemical kinetic parameters were found to be not remarkably far from those determined for commercial Pt/C (–10 mV vs. RHE, 0.88 mA cm–2, 108 mV dec–1 and 110 mV to yield a current density of 10 mA cm–2). In addition, the most active molecular electro-catalysts for H2 production from aqueous alkaline electrolytes were found to be comparable to the HER electrochemical kinetic parameters reported here for the GC–Zn2 electrocatalyst. Using 5000 cycles of repetitive cyclic voltammetry and 48 h of chronoamperometry measurements, the best electrocatalyst’s stability and long term durability were tested. It exhibited high stability for the HER catalytic activity.
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Bhattacharya, Deepra, i Christopher G. Arges. "Fabrication of Block Copolymer Templated Extended Surface Model Electrocatalysts By Atomic Layer Deposition and Physical Vapor Deposition". ECS Meeting Abstracts MA2022-02, nr 31 (9.10.2022): 1153. http://dx.doi.org/10.1149/ma2022-02311153mtgabs.
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Templating platinum group metal (PGM) nanostructures from microphase separated block copolymers (BCPs) allows for electrocatalytic activity to be studied on highly ordered, model surfaces with precisely controlled feature sizes and morphologies, thereby allowing catalyst electroactivity and stability to be probed as a function of nanoscale geometry. In our previous work [1], BCP templated electrocatalysts fabricated via incipient wetness impregnation of PGM precursors were tested for hydrogen oxidation/evolution and water-splitting activity on interdigitated electrodes using liquid and solid polymer electrolytes. This talk presents the fabrication of such electrocatalysts via Atomic Layer Deposition (ALD) and Physical Vapor Deposition (PVD) techniques (e-beam evaporation and sputtering). Self-assembled lamellae of poly-(styrene-block-methylmethacrylate) (PSbPMMA) thin films on Si wafer and glassy carbon substrates were subjected to 5 - 15 ALD cycles with trimethylaluminium (TMA) precursor to induce selective growth of alumina in the PMMA domains via Sequential Infiltration Synthesis. Thereafter, the polymer template was removed via Reactive Ion Etching (RIE) with oxygen plasma. The resultant alumina nanostructures templated from self-assembled PSbPMMA was then used as a substrate either for Platinum ALD with (trimethyl)methylcyclopentadienylplatinum(IV) precursor atop a Titanium Nitride adhesive layer, or for sputtering of Pt atop a Ti adhesive layer to obtain conformal Pt coatings of up to 20 nm in thickness. When e-beam evaporation was used, The PMMA domains were selectively removed by successive wet and dry etch steps, followed by deposition and lift-off. The PGM electrocatalyst nanostructures were characterized via a combination of electron microcopy, X-ray diffraction, and X-ray photoelectron spectroscopy, and the Pt content of the catalysts were determined via microwave leaching and digestion of the electrocatalyst thin film followed by Inductively Coupled Plasma Mass Spectroscopy. The nanostructured electrocatalysts were tested for oxygen reduction (ORR) activity in a conventional rotating disk electrode setup using 0.1 M perchloric acid electrolyte, and the ORR mass activities and active surface area were obtained. [1] Bhattacharya, D., Arges, C. G., et al., Small, 2021, 17, 2100437
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Kuzikov, A. V., T. V. Bulko, P. I. Koroleva, R. A. Masamrekh, S. S. Babkina, A. A. Gilep i V. V. Shumyantseva. "Electroanalytical and electrocatalytical characteristics of cytochrome P450 3A4 using electrodes modified with nanocomposite carbon nanomaterials". Biomeditsinskaya Khimiya 66, nr 1 (styczeń 2020): 64–70. http://dx.doi.org/10.18097/pbmc20206601064.
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The electroanalytical characteristics of recombinant cytochrome P450 3A4 (P450 3A4) immobilized on the surface of screen-printed graphite electrodes modified with multi-walled carbon nanotubes have been studied. The role and the influence of graphite working electrode modification with carbon nanotubes on electroanalytical characteristics of cytochrome P450 3A4 have been demonstrated. The conditions for the immobilization of cytochrome P450 3A4 on the obtained screen-printed graphite electrodes modified with carbon multi-walled nanotubes have been optimized. The electrochemical parameters of the oxidation and reduction of the heme iron of the enzyme have been estimated. The midpoint potential E0′ was -0.35±0.01 V vs Ag/AgCl; the calculated heterogeneous electron transfer rate constant ks, was 0.57±0.04 s-1; the amount of electroactive cytochrome P450 3A4 on the electrode Г0, was determined as (2.6±0.6)⋅10-10 mol/cm2. The functioning mechanism of P450 3A4-based electrochemical sensor followed the “protein film voltammetry”. In order to develop electrochemical analysis of drugs being substrates of that hemoprotein and respective medical biosensors the voltammetric study of catalytic activity of immobilized cytochrome P450 3A4 was carried out. Electrocatalytic properties of cytochrome P450 3A4, immobilized on modified screen-printed graphite electrodes, has been investigated using erythromycin (macrolide antibiotics). It has been shown that the modification of electrodes plays a decisive role for the study of the properties of cytochromes P450 in electrochemical investigations. Smart electrodes can serve as sensors for analytical purposes, as well as electrocatalysts for the study of biotransformation processes and metabolic processes. Electrodes modified with carbon nanomaterials are applicable for analytical purposes in the registration of hemoproteins. Electrodes modified with synthetic membrane-like compounds (e.g. didodecyldimethylammonium bromide) are effective in enzyme-dependent electrocatalysis.
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Hatahet, Mhamad Hamza, Hagen Bryja, Andriy Lotnyk, Maximilian Wagner i Bernd Abel. "Ultra-Low Loading of Iron Oxide and Platinum on CVD-Graphene Composites as Effective Electrode Catalysts for Solid Acid Fuel Cells". Catalysts 13, nr 8 (26.07.2023): 1154. http://dx.doi.org/10.3390/catal13081154.
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We propose a new design for electrocatalysts consisting of two electrocatalysts (platinum and iron oxide) that are deposited on the surfaces of an oxidized graphene substrate. This design is based on a simple structure where the catalysts were deposited separately on both sides of oxidized graphene substrate; while the iron oxide precipitated out of the etching solution on the bottom-side, the surface of the oxidized graphene substrate was decorated with platinum using the atomic layer deposition technique. The Fe2O3-decorated CVD-graphene composite exhibited better hydrogen electrooxidation performance (area-normalized electrode resistance (ANR) of ~600 Ω·cm−2) and superior stability in comparison with bare-graphene samples (ANR of ~5800 Ω·cm−2). Electrochemical impedance measurements in humidified hydrogen at 240 °C for (Fe2O3|Graphene|Platinum) electrodes show ANR of ~0.06 Ω·cm−2 for a platinum loading of ~60 µgPt·cm−2 and Fe2O3 loading of ~2.4 µgFe·cm−2, resulting in an outstanding mass normalized activity of almost 280 S·mgPt−1, exceeding even state-of-the-art electrodes. This ANR value is ~30% lower than the charge transfer resistance of the same electrode composition in the absence of Fe2O3 nanoparticles. Detailed study of the Fe2O3 electrocatalytic properties reveals a significant improvement in the electrode’s activity and performance stability with the addition of iron ions to the platinum-decorated oxidized graphene cathodes, indicating that these hybrid (Fe2O3|Graphene|Platinum) materials may serve as highly efficient catalysts for solid acid fuel cells and beyond.
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Chen, Jun Jie, i De Guang Xu. "Recent Development and Applications in Electrodes for URFC". International Letters of Chemistry, Physics and Astronomy 47 (luty 2015): 165–77. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.47.165.
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The design of electrodes for URFC (unitised regenerative polymer electrolyte fuel cells) requires a delicate balancing of transport media. Gas transport, electrons and protons must be carefully optimised to provide efficient transport to and from the electrochemical reaction sites. This review is a survey of recent literature with the objective to identify common components and design and assembly methods for URFC electrodes, focusing primarily on the development of a better performing bifunctional electrocatalyst for the oxygen reduction and water oxidation. Advances in unitised regenerative fuel cells study have yielded better performing oxygen electrocatalysts capable of improving energy efficiency with longer endurance and less performance degradation over time. Fuel cells using these electrocatalyst have a possible future as a source of energy.
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Chen, Jun Jie, i De Guang Xu. "Recent Development and Applications in Electrodes for URFC". International Letters of Chemistry, Physics and Astronomy 47 (24.02.2015): 165–77. http://dx.doi.org/10.56431/p-o13q11.
Pełny tekst źródłaStreszczenie:
The design of electrodes for URFC (unitised regenerative polymer electrolyte fuel cells) requires a delicate balancing of transport media. Gas transport, electrons and protons must be carefully optimised to provide efficient transport to and from the electrochemical reaction sites. This review is a survey of recent literature with the objective to identify common components and design and assembly methods for URFC electrodes, focusing primarily on the development of a better performing bifunctional electrocatalyst for the oxygen reduction and water oxidation. Advances in unitised regenerative fuel cells study have yielded better performing oxygen electrocatalysts capable of improving energy efficiency with longer endurance and less performance degradation over time. Fuel cells using these electrocatalyst have a possible future as a source of energy.
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Drasbæk, Daniel B., Märtha M. Welander, Marie L. Traulsen, Bhaskar R. Sudireddy, Peter Holtappels i Robert A. Walker. "Operando characterization of metallic and bimetallic electrocatalysts for SOFC fuel electrodes operating under internal methane reforming conditions". Journal of Materials Chemistry A 10, nr 10 (2022): 5550–60. http://dx.doi.org/10.1039/d1ta07299d.
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Working solid oxide fuel cell anodes based on conducting ceramic scaffolds with different infiltrated electrocatalysts have been investigated by operando Raman spectroscopy and EIS. Carbon deposition depends on electrical load and electrocatalyst.
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Warczak, Magdalena, Maciej Gryszel, Marie Jakešová, Vedran Đerek i Eric Daniel Głowacki. "Organic semiconductor perylenetetracarboxylic diimide (PTCDI) electrodes for electrocatalytic reduction of oxygen to hydrogen peroxide". Chemical Communications 54, nr 16 (2018): 1960–63. http://dx.doi.org/10.1039/c7cc08471d.
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Organic semiconductors can give high electrocatalytic currents while retaining excellent stability. We demonstrate the use of the industrial pigment PTCDI as a robust electrocatalyst for oxygen-to-peroxide electrolyzers operating at state-of-the-art efficiency.
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Thi Mo, Nguyen, Nguyen Minh Chau, Nguyen Minh Bach, Pham Quang Duc i Hoang Van Hung. "Electrochemical Synthesis of Efficient Catalyst Ni-Fe on Ni Foam for Electrochemical Water Splitting". Asian Journal of Chemistry 35, nr 8 (2023): 1916–20. http://dx.doi.org/10.14233/ajchem.2023.24056.
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Herein, the Ni-Fe electrocatalysts dispersed on nickel foam (NF) were successfully synthesized by the electrodeposition method. The electrode materials were characterized by XRD, EDX and SEM techniques. Electrochemical analysis was performed to determine the electrocatalytic properties for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) of the overall water splitting. The results indicate that the NiFe/NF electrode exhibits superior electrocatalytic activity as compared to the Ni/Fe and Fe/NF electrodes for both OER and HER with a significantly lower overpotential, 300 mV to reach 10 mA cm–2 with OER and 364 mV to reach −20 mA cm–2 with HER.
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Zhang, Yuqing, Zilu Jin, Lijun Chen i Jiaqi Wang. "SrFexNi1−xO3−δ Perovskites Coated on Ti Anodes and Their Electrocatalytic Properties for Cleaning Nitrogenous Wastewater". Materials 12, nr 3 (8.02.2019): 511. http://dx.doi.org/10.3390/ma12030511.
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Perovskites (ABO3), regarded as the antioxidative anode materials in electrocatalysis to clean nitrogenous wastewater, show limited oxygen vacancies and conductivity due to their traditional semiconductor characteristic. To further improve the conductivity and electrocatalytic activity, the ferrum (Fe) element was first doped into the SrNiO3 to fabricate the SrFexNi1−xO3−δ perovskites, and their optimum fabrication conditions were determined. SrFexNi1−xO3−δ perovskites were coated on a titanium (Ti) plate to prepare the SrFexNi1−xO3−δ/Ti electrodes. Afterward, one SrFexNi1−xO3−δ/Ti anode and two stainless steel cathodes were combined to assemble the electrocatalytic reactor (ECR) for cleaning simulated nitrogenous wastewater ((NH4)2SO4 solution, initial total nitrogen (TN) concentration of 150 mg L–1). Additionally, SrFexNi1−xO3−δ materials were characterized using Fourier Transform Infrared (FT-IR), Raman spectra, X-Ray Diffraction (XRD), Energy Dispersive X-ray (EDX), Electrochemical Impedance Spectroscopy (EIS) and Tafel curves, respectively. The results indicate that SrFexNi1−xO3−δ materials are featured with the perovskite crystal structure and Fe is appreciably doped into SrNiO3. Moreover, the optimum conditions for fabricating SrFexNi1−xO3−δ were the reaction time of 120 min for citrate sol-gel, a calcination temperature of 700 °C, and Fe doping content of x = 0.3. SrFe0.3Ni0.7O2.85, and perovskite performs attractive electrocatalytic activity (TN removal ratio of 91.33%) and ECR conductivity of 3.62 mS cm−1 under an electrocatalytic time of 150 min. Therefore, SrFexNi1−xO3−δ perovskites are desirable for cleaning nitrogenous wastewater in electrocatalysis.
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Woo, Seongwon, Jooyoung Lee, Dong Sub Lee, Jung Kyu Kim i Byungkwon Lim. "Electrospun Carbon Nanofibers with Embedded Co-Ceria Nanoparticles for Efficient Hydrogen Evolution and Overall Water Splitting". Materials 13, nr 4 (13.02.2020): 856. http://dx.doi.org/10.3390/ma13040856.
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In this study, simple electrospinning combined with pyrolysis were used to fabricate transition-metal-based-nanoparticle-incorporated carbon nanofiber (CNF) electrocatalysts for a high-efficiency hydrogen evolution reaction (HER) and overall water splitting. Co-CeO2 nanoparticle-incorporated carbon nanofibers (Co-CeO2@CNF) exhibit an outstanding electrocatalytic HER performance with an overpotential and Tafel slope of 92 mV and 54 mV/dec, respectively. For the counterpart, electrolysis, we incorporate the widely used Ni2Fe catalyst with a high oxygen evolution reaction (OER) activity into the carbon nanofiber (Ni2Fe@CNF). To evaluate their electrochemical properties for the overall water splitting, Co-CeO2@CNF and Ni2Fe@CNF were used as the HER and OER electrocatalysts in an alkaline electrolyzer. With the paired Co-CeO2@CNF and Ni2Fe@CNF electrodes, an overall water splitting current density of 10 mA/cm2 was achieved by applying 1.587 V across the electrodes with a remarkably lower overpotential of 257 mV compared to that of an electrolyzer comprised of Pt/C and IrO2 electrodes (400 mV). Owing to the conformal incorporation of nanoparticles into the CNF, the electrocatalysts exhibit significant long-term durability over 70 h of overall water splitting. This study provides rational designs of catalysts with high electrochemical catalytic activity and durability to achieve overall water splitting.
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Lafuente, Esperanza, Edgar Muñoz, Ana M. Benito, Wolfgang K. Maser, M. Teresa Martínez, Francisco Alcaide, Larraitz Ganborena i in. "Single-walled carbon nanotube-supported platinum nanoparticles as fuel cell electrocatalysts". Journal of Materials Research 21, nr 11 (listopad 2006): 2841–46. http://dx.doi.org/10.1557/jmr.2006.0355.
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Single-walled carbon nanotubes (SWNTs) have been used as electrocatalyst support for fuel cells. A toluene solution of a platinum salt, bis(dibenzylideneacetone) platinum, has been used for the first time to decorate the outer surface of SWNT bundles with Pt nanoparticles. The obtained Pt/SWNT materials were then used as catalytic layer in electrodes for fuel cell electrocatalysis. The used platinum salt concentration in the initial SWNT dispersion determined the Pt nanoparticle size and, consequently, the activity of the Pt/SWNT electrodes toward the oxygen reduction reaction. The achieved results were compared with those corresponding to a commercial Pt/carbon black catalyst with similar Pt loading and surface area.
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Jacobse, Leon, Ralf Schuster, Johannes Pfrommer, Xin Deng, Silvan Dolling, Tim Weber, Olof Gutowski i in. "A combined rotating disk electrode–surface x-ray diffraction setup for surface structure characterization in electrocatalysis". Review of Scientific Instruments 93, nr 6 (1.06.2022): 065111. http://dx.doi.org/10.1063/5.0087864.
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Characterizing electrode surface structures under operando conditions is essential for fully understanding structure–activity relationships in electrocatalysis. Here, we combine in a single experiment high-energy surface x-ray diffraction as a characterizing technique with a rotating disk electrode to provide steady state kinetics under electrocatalytic conditions. Using Pt(111) and Pt(100) model electrodes, we show that full crystal truncation rod measurements are readily possible up to rotation rates of 1200 rpm. Furthermore, we discuss possibilities for both potentiostatic as well as potentiodynamic measurements, demonstrating the versatility of this technique. These different modes of operation, combined with the relatively simple experimental setup, make the combined rotating disk electrode–surface x-ray diffraction experiment a powerful technique for studying surface structures under operando electrocatalytic conditions.
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Fan, Minmin, Peixiao Li, Baibai Liu, Yun Gong, Chengling Luo, Kun Yang, Xinjuan Liu, Jinchen Fan i Yuhua Xue. "Interface Coordination Engineering of P-Fe3O4/Fe@C Derived from an Iron-Based Metal Organic Framework for pH-Universal Water Splitting". Nanomaterials 13, nr 13 (22.06.2023): 1909. http://dx.doi.org/10.3390/nano13131909.
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Developing electrocatalysts with high energy conversion efficiency is urgently needed. In this work, P-Fe3O4/Fe@C electrodes with rich under-coordinated Fe atom interfaces are constructed for efficient pH-universal water splitting. The introduction of under-coordinated Fe atoms into the P-Fe3O4/Fe@C interface can increase the local charge density and polarize the 3d orbital lone electrons, which promotes water adsorption and activation to release more H*, thus elevating electrocatalytic activity. As a donor-like catalyst, P-Fe3O4/Fe@C displays excellent electrocatalytic performance with overpotentials of 160 mV and 214 mV in acidic and alkaline electrolytes at 10 mA cm−2, in addition to pH-universal long-term stability.
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Shi, Hang, Yi-Tong Zhou, Rui-Qi Yao, Wu-Bin Wan, Qing-Hua Zhang, Lin Gu, Zi Wen, Xing-You Lang i Qing Jiang. "Intermetallic Cu5Zr Clusters Anchored on Hierarchical Nanoporous Copper as Efficient Catalysts for Hydrogen Evolution Reaction". Research 2020 (20.02.2020): 1–12. http://dx.doi.org/10.34133/2020/2987234.
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Designing highly active and robust platinum-free electrocatalysts for hydrogen evolution reaction is vital for large-scale and efficient production of hydrogen through electrochemical water splitting. Here, we report nonprecious intermetallic Cu5Zr clusters that are in situ anchored on hierarchical nanoporous copper (NP Cu/Cu5Zr) for efficient hydrogen evolution in alkaline medium. By virtue of hydroxygenated zirconium atoms activating their nearby Cu-Cu bridge sites with appropriate hydrogen-binding energy, the Cu5Zr clusters have a high electrocatalytic activity toward the hydrogen evolution reaction. Associated with unique architecture featured with steady and bicontinuous nanoporous copper skeleton that facilitates electron transfer and electrolyte accessibility, the self-supported monolithic NP Cu/Cu5Zr electrodes boost violent hydrogen gas release, realizing ultrahigh current density of 500 mA cm-2 at a low potential of -280 mV versus reversible hydrogen electrode, with exceptional stability in 1 M KOH solution. The electrochemical properties outperform those of state-of-the-art nonprecious metal electrocatalysts and make them promising candidates as electrodes in water splitting devices.
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Escudero-Escribano, Maria. "(Invited) Tailored Electrochemical Interfaces for the Production of Renewable Fuels". ECS Meeting Abstracts MA2022-01, nr 36 (7.07.2022): 1601. http://dx.doi.org/10.1149/ma2022-01361601mtgabs.
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Tailoring the structure of the electrochemical interface at the atomic level is key to design new electrocatalysts for renewable energy conversion and storage. This talk will focus on novel catalyst materials and engineered interfaces for electrochemical energy conversion. In particular, I will discuss structure sensitivity and electrolyte effects for oxygen and carbon dioxide/carbon monoxide electrocatalysis. First, I will present our work toward understanding the structure-activity-stability relations on high surface area nanostructured Ir-based materials for oxygen evolution. Then, I will highlight the importance of carrying out model studies on Cu-based surfaces to understand the structure-properties relations for CO2 and CO reduction. We have investigated the effect of pH, specific anion adsorption and potential dependence for CO reduction on Cu single-crystalline electrodes. We show how well defined studies are essential to design efficient electrocatalysts for the production of renewable fuels.
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Ekspong, Joakim, i Thomas Wågberg. "Stainless Steel as A Bi-Functional Electrocatalyst—A Top-Down Approach". Materials 12, nr 13 (2.07.2019): 2128. http://dx.doi.org/10.3390/ma12132128.
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For a hydrogen economy to be viable, clean and economical hydrogen production methods are vital. Electrolysis of water is a promising hydrogen production technique with zero emissions, but suffer from relatively high production costs. In order to make electrolysis of water sustainable, abundant, and efficient materials has to replace expensive and scarce noble metals as electrocatalysts in the reaction cells. Herein, we study activated stainless steel as a bi-functional electrocatalyst for the full water splitting reaction by taking advantage of nickel and iron suppressed within the bulk. The final electrocatalyst consists of a stainless steel mesh with a modified surface of layered NiFe nanosheets. By using a top down approach, the nanosheets stay well anchored to the surface and maintain an excellent electrical connection to the bulk structure. At ambient temperature, the activated stainless steel electrodes produce 10 mA/cm2 at a cell voltage of 1.78 V and display an onset for water splitting at 1.68 V in 1M KOH, which is close to benchmarking nanosized catalysts. Furthermore, we use a scalable activation method using no externally added electrocatalyst, which could be a practical and cheap alternative to traditionally catalyst-coated electrodes.
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Quinson, Jonathan, Ricardo Hidalgo, Philip A. Ash, Frank Dillon, Nicole Grobert i Kylie A. Vincent. "Comparison of carbon materials as electrodes for enzyme electrocatalysis: hydrogenase as a case study". Faraday Discuss. 172 (2014): 473–96. http://dx.doi.org/10.1039/c4fd00058g.
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We present a study of electrocatalysis by an enzyme adsorbed on a range of carbon materials, with different size, surface area, morphology and graphitic structure, which are either commercially available or prepared via simple, established protocols. We choose as our model enzyme the hydrogenase I from E. coli (Hyd-1), which is an active catalyst for H2 oxidation, is relatively robust and has been demonstrated in H2 fuel cells and H2-driven chemical synthesis. The carbon materials were characterised according to their surface area, surface morphology and graphitic character, and we use the electrocatalytic H2 oxidation current for Hyd-1 adsorbed on these materials to evaluate their effectiveness as enzyme electrodes. Here, we show that a variety of carbon materials are suitable for adsorbing hydrogenases in an electroactive configuration. This unified study provides insight into selection and design of carbon materials for study of redox enzymes and different applications of enzyme electrocatalysis.
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Yuan, Baiqing, Liju Gan, Gang Li, Chunying Xu i Gang Liu. "A Micro Electrochemical Sensor for Multi-Analyte Detection Based on Oxygenated Graphene Modified Screen-Printed Electrode". Nanomaterials 12, nr 4 (21.02.2022): 711. http://dx.doi.org/10.3390/nano12040711.
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Electrode interfaces with both antibiofouling properties and electrocatalytic activity can promote the practical application of nonenzymatic electrochemical sensors in biological fluids. Compared with graphene, graphene oxide (GO) possesses unique properties such as superior solubility (hydrophilicity) in water, negative charge, and abundant oxygenated groups (oxo functionalities) in the plane and edge sites, which play an essential role in electrocatalysis and functionalization. In this work, a micro electrochemical sensor consisting of GO-modified screen-printed electrode and PDMS micro-cell was designed to achieve multi-analyte detection with excellent selectivity and anti-biofouling properties by electrochemically tuning the oxygen-containing functional species, hydrophilicity/hydrophobicity, and electrical conductivity. In particular, the presented electrodes demonstrated the potential in the analysis of biological samples in which electrodes often suffer from serious biofouling. The interaction of proteins with electrodes as well as uric acid was investigated and discussed.
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Sun, Chia-Liang, Jheng-Sin Su, Shun-Yi Lai i Yu-Jen Lu. "Size Effects of Pt Nanoparticle/Graphene Composite Materials on the Electrochemical Sensing of Hydrogen Peroxide". Journal of Nanomaterials 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/861061.
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The electrochemical detection of hydrogen peroxide (H2O2) has attracted much attention recently. Meanwhile, the size of nanoparticles which significantly influences electrocatalytic activity is crucial for electrocatalysts. Hence, we prepared five different size-selected Pt/graphene-modified glassy carbon (GC) electrodes to characterize H2O2level via electrochemical measurements. During the preparation of the nanocomposites, size-selected Pt nanoparticles (NPs) with the mean diameter of 1.3, 1.7, 2.9, and 4.3 nm were assembled onto the graphene surfaces. The electrochemical measurement results are size-dependent for Pt NPs when sensing H2O2. When all cyclic voltammogram results from various electrodes are compared, the Pt-1.7 nm/G-modified GC electrode has the highest reduction current, the best detection limit, and the best sensitivity.
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Nishimoto, Takeshi, Tatsuya Shinagawa i Kazuhiro Takanabe. "(Digital Presentation) Nickel-Iron Electrocatalysts Modified with Group 11 Metals Achieving 1 A cm−2 of Oxygen Evolution in Buffered Near-Neutral pH Electrolyte". ECS Meeting Abstracts MA2022-01, nr 36 (7.07.2022): 1557. http://dx.doi.org/10.1149/ma2022-01361557mtgabs.
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Electrocatalytic processes driven by the renewable electricity will play a pivotal role to achieve sustainable in our society, whereby the thermodynamically stable chemicals are converted into value-added products or energy carriers. For instance, the water electrolysis produces green hydrogen, and the carbon dioxide electrolysis yields commodity chemicals such as ethylene or carbon monoxide.[1] These processes commonly share an anodic half-reaction of oxygen evolution reaction (OER) that requires large overpotentials due to its slow kinetics, leading to the significant loss of overall energy efficiency.[2] This is particularly the case at near-neutral pH,[3] which however is likely the desired condition for electrocatalytic CO2 reduction due to the lessened loss of carbon dioxide via carbonate formation that prevails in alkaline conditions.[4] Toward the large-scale operation of these technologies, it is highly desired to develop an active, stable, and earth-abundant metal based electrocatalyst that catalyzes the OER at near-neutral pH and high current densities. The present study reports on our discovery of the transition metal-based electrocatalysts that efficiently catalyze OER in carbonate buffer electrolyte at near-neutral pH. Firstly, a variety of electrodes were fabricated by electro-deposition of transition metals (manganese, iron, cobalt, copper) on electrochemically activated Ni (ECA-Ni) substrates[5] with nanostructured surface. Their electrocatalytic testing revealed that iron oxide (Fe-O) modified ECA-Ni achieved a current density of 100 mA cm−2 at an overpotential of ca. 280 mV in dense electrolyte of 1.5 mol kg−1 K-carbonate solution and 353 K, whose pH was adjusted to pH 10.5 at 298 K prior to the testing. This pH level was essential to achieve stable operation using the Ni-Fe electrode. Subsequently, group 11 metals of copper, silver, or gold were introduced into Fe-O/ECA-Ni via co-electrodeposition to tailor the nature of active site for improved OER. Remarkably, electrodes of Fe-Cu-O/ECA-Ni and Fe-Au-O/ECA-Ni catalyzed the OER at a rate of 1 A cm−2 and an overpotential of ca. 330 mV, whose figure is comparable to those in extremely alkaline conditions (Figure 1). Long-term and on-off stability testing revealed that the developed electrodes maintained its performance. Our characterization on double-layer capacitance indicated the enlarged surface area of Fe-Cu-O and Fe-Au-O electrodes with respect to the pristine Fe-O counterparts, which partly contributed to the improved OER performance. In addition, ex situ X-ray photoelectron spectroscopy and in situ X-ray absorption spectroscopy concurrently pointed to the presence of stable Fe(III) species for Fe-Cu-O/ECA-Ni, plausibly FeOOH. The present study discovered transition metal based electrocatalysts for the OER at near-neutral pH and high current densities, achieving comparable performance to those in alkaline conditions, which is significant given the merits of near-neutral pH condition for CO2 reduction. These findings represent the potentiality of near-neutral pH electrochemical system on industrial scale, which can help to construct a sustainable society. Reference [1] S. Chu, A. Majumdar, Nature 2012, 488, 294. [2] T. Reier, H. N. Nong, D. Teschner, R. Schlögl, P. Strasser, Adv. Energy Mater. 2017, 7, 1601275. [3] T. Nishimoto, T. Shinagawa, T. Naito, K. Takanabe, ChemSusChem 2021, 14, 1554. [4] J. A. Rabinowitz, M. W. Kanan, Nat. Commun. 2020, 11, 5231. [5] T. Shinagawa, M. T.-K. Ng, K. Takanabe, Angew. Chem. Int. Ed. 2017, 56, 5061. Figure 1
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Chen, Neng, Sai Che, Hongchen Liu, Na Ta, Guohua Li, Fengjiang Chen, Guang Ma, Fan Yang i Yongfeng Li. "In Situ Growth of Self-Supporting MOFs-Derived Ni2P on Hierarchical Doped Carbon for Efficient Overall Water Splitting". Catalysts 12, nr 11 (27.10.2022): 1319. http://dx.doi.org/10.3390/catal12111319.
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The in situ growth of metal organic framework (MOF) derivatives on the surface of nickel foam is a novel type of promising self-supporting electrode catalyst. In this paper, this work reports for the first time the strategy of in situ growth of Ni-MOF, where the metal source is purely provided by a nickel foam (NF) substrate without any external metal ions. MOF-derived Ni2P/NPC structure is achieved by the subsequent phosphidation to yield Ni2P on porous N, P-doped carbon (NPC) backbone. Such strategy provides the as-synthesized Ni2P/NPC/NF electrocatalyst an extremely low interfacial steric resistance. Moreover, a unique three-dimensional hierarchical structure is achieved in Ni2P/NPC/NF, providing massive active sites, short ion diffusion path, and high electrical conductivity. Directly applied as the electrode, Ni2P/NPC/NF demonstrates excellent electrocatalytic performance towards both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), with low overpotentials of only 58 mV and 208 mV to drive 10 mA cm−2, respectively, in 1 M KOH. Furthermore, Ni2P/NPC/NF acting as the overall water splitting electrodes can generate a current density of 10 mA cm−2 at an ultralow cell voltage of 1.53 V. This simple strategy paves the way for the construction of self-supporting transition metal-based electrocatalysts.
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Al Mamun, Mohammad, Yasmin Abdul Wahab, Hossain Hossain, Abu Hashem i Mohd Rafie Johan. "Scrap Gold Recovery: Recycling, Fabrication and Electrochemical Characterization of Low-Cost Gold Electrode". Malaysian Catalysis-An International Journal 2, nr 1 (21.10.2022): 1–20. http://dx.doi.org/10.22452/mcij.vol2no1.1.
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As a noble metal, gold is considered the most popular material in electrocatalysis. In spite of that, this metal is a highly expensive material in the manufacture of low-cost appliances. In the present work, scrap gold, produced in jewellery as waste, is introduced as a low-cost resource of gold to be recycled. A gold electrode was fabricated by connecting the tablet shaped recycled gold with copper wire inserting into a polytetrafluoroethylene (PTFE) tube. The manufactured electrodes are easily renewable, modifiable with nanomaterials and show excellent electrochemical characteristics in presence of redox species. The CV (cyclic voltammetry), DPV (differential pulse voltammetry), and EIS (electrochemical impedance spectroscopic) analysis data also infer that the developed recycled gold-based electrodes would be suitable for the development of low-cost electrocatalytic sensors devices.
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Chen, Tse-Wei, Shen-Ming Chen, Ganesan Anushya, Ramanujam Kannan, Pitchaimani Veerakumar, Mohammed Mujahid Alam, Saranvignesh Alargarsamy i Rasu Ramachandran. "Metal-Oxides- and Metal-Oxyhydroxides-Based Nanocomposites for Water Splitting: An Overview". Nanomaterials 13, nr 13 (5.07.2023): 2012. http://dx.doi.org/10.3390/nano13132012.
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Water electrolysis is an important alternative technology for large-scale hydrogen production to facilitate the development of green energy technology. As such, many efforts have been devoted over the past three decades to producing novel electrocatalysis with strong electrochemical (EC) performance using inexpensive electrocatalysts. Transition metal oxyhydroxide (OxH)-based electrocatalysts have received substantial interest, and prominent results have been achieved for the hydrogen evolution reaction (HER) under alkaline conditions. Herein, the extensive research focusing on the discussion of OxH-based electrocatalysts is comprehensively highlighted. The general forms of the water-splitting mechanism are described to provide a profound understanding of the mechanism, and their scaling relation activities for OxH electrode materials are given. This paper summarizes the current developments on the EC performance of transition metal OxHs, rare metal OxHs, polymers, and MXene-supported OxH-based electrocatalysts. Additionally, an outline of the suggested HER, OER, and water-splitting processes on transition metal OxH-based electrocatalysts, their primary applications, existing problems, and their EC performance prospects are discussed. Furthermore, this review article discusses the production of energy sources from the proton and electron transfer processes. The highlighted electrocatalysts have received substantial interest to boost the synergetic electrochemical effects to improve the economy of the use of hydrogen, which is one of best ways to fulfill the global energy requirements and address environmental crises. This article also provides useful information regarding the development of OxH electrodes with a hierarchical nanostructure for the water-splitting reaction. Finally, the challenges with the reaction and perspectives for the future development of OxH are elaborated.
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Davi, Martin, Tim Schultze, Denise Kleinschmidt, Frank Schiefer, Birgit Hahn i Adam Slabon. "Gold nanocrystal arrays as electrocatalysts for the oxidation of methanol and ethanol". Zeitschrift für Naturforschung B 71, nr 7 (1.07.2016): 821–25. http://dx.doi.org/10.1515/znb-2016-0032.
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AbstractA general difficulty in the comparison of catalysts regarding their electrochemical activities is the significant dependency on the electrode preparation method. In addition to single-crystal, thin-film, and polycrystalline electrodes, most electrocatalysts contain a physical mixture of catalytically active nanocrystals (NCs), conductive carbon support, and binding agent. This type of preparation makes the agglomeration of NCs to larger entities inevitable and simultaneously decreases the catalytically active surface area. In this work, electocatalysts based on two-dimensional arrays of self-assembled monodisperse Au NCs with a particle size of 8 nm have been fabricated. Their electrocatalytic performance in the electrochemical oxidation reaction of methanol and ethanol was investigated for different pH values. The self-assembly of Au NCs into two-dimensional arrays enables to fabricate electrocatalysts with a high mass activity in alkaline electrolytes for alcohol oxidation reactions.
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Alaufey, Rayan, i Maureen H. Tang. "A Mechanistic Investigation of Electrochemical Ozone Production Using Nickel and Antimony Doped Tin Oxide in Non-Aqueous Electrolytes". ECS Meeting Abstracts MA2022-02, nr 64 (9.10.2022): 2389. http://dx.doi.org/10.1149/ma2022-02642389mtgabs.
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Electrochemical water splitting to produce hydrogen has attracted great interest as an environmentally-friendly renewable fuel. While cathodic hydrogen evolution (HER) is a relatively fast process that produces a valuable chemical, the anodic oxygen evolution reaction (OER) is a slow process that adds little to no economic value to water splitting.1,2 Generating a high-performance oxidizer such as ozone instead of oxygen could make water splitting more economically feasible because of the added value of ozone. However, electrochemical ozone production (EOP) catalysts are typically hindered by low current efficiencies, poor selectivity, low stability, and high energy demands, which limit the industrial application of this reaction.3,4 Further improvements in catalyst performance could be achieved by better understanding the mechanism of ozone production. Nickel and antimony doped tin oxide (Ni/Sb-SnO2, NATO) is currently reported to have the highest EOP current efficiency at room temperature. However, the mechanism of EOP on NATO electrodes has not yet been established. A primary complication when studying the mechanism of EOP using NATO electrocatalysts in water is that oxygen atoms in the ozone molecule can originate from sources other than water, such as dissolved molecular oxygen or the electrocatalyst oxide lattice.1,5,6 In this work, lattice oxygen participation in EOP is investigated by replacing water with acetonitrile, a polar aprotic solvent without oxygen atoms. Our results show that ozone can be generated in acetonitrile in similar quantities as aqueous conditions.2 These quantities are inconsistent with a 6-electron process based on calculated current efficiencies. Furthermore, the addition of small quantities of water is shown to have a negative impact on ozone generation. The origin of this impact is thought to not be mechanistic in nature. Instead, we suggest that adding water to the mixture leads to the generation of hydroxide ions which act as ozone scavengers. To our knowledge, this is the first report of electrochemical ozone production in a non-aqueous solvent. Future work will more conclusively determine the origin of oxygen atoms using isotopic labeling. Furthermore, the ability of nonaqueous solvents to stabilize reactive oxygen species and impact selectivity will be investigated. Utilizing the knowledge gained by studying ozone generation in nonaqueous solvents, it might be possible to design a better EOP system which could enhance the applicability of this reaction. (1) Lees, C. M.; Lansing, J. L.; Morelly, S. L.; Lee, S. E.; Tang, M. H. Ni- and Sb-Doped SnO2 Electrocatalysts with High Current Efficiency for Ozone Production via Electrodeposited Nanostructures. J. Electrochem. Soc. 2018, 165 (16), E833. https://doi.org/10.1149/2.0051816jes. (2) James L. Lansinga±, Lingyan Zhaob, Tana Siboonruanga, N. Harsha Attanayakea, Angela B. Leob, Peter Fatourosb, So Min Parkc, Kenneth R. Grahamc, John A. Keithb, Maureen Tang*a. Gd-Ni-Sb-SnO2 Electrocatalysts for Active and Selective Ozone Production. (3) Christensen, P. A.; Attidekou, P. S.; Egdell, R. G.; Maneelok, S.; Manning, D. A. C.; Palgrave, R. Identification of the Mechanism of Electrocatalytic Ozone Generation on Ni/Sb-SnO 2. J. Phys. Chem. C 2017, 121 (2), 1188–1199. https://doi.org/10.1021/acs.jpcc.6b10521. (4) Wang, Y.-H.; Chen, Q.-Y. Anodic Materials for Electrocatalytic Ozone Generation. Int. J. Electrochem. 2013, 2013, 1–7. https://doi.org/10.1155/2013/128248. (5) Jiang, W.; Wang, S.; Liu, J.; Zheng, H.; Gu, Y.; Li, W.; Shi, H.; Li, S.; Zhong, X.; Wang, J. Lattice Oxygen of PbO 2 Induces Crystal Facet Dependent Electrochemical Ozone Production. J. Mater. Chem. A 2021, 9 (14), 9010–9017. https://doi.org/10.1039/D0TA12277G. (6) Feng, J.; Johnson, D. C.; Lowery, S. N.; Carey, J. J. Electrocatalysis of Anodic Oxygen‐Transfer Reactions: Evolution of Ozone. J. Electrochem. Soc. 1994, 141 (10), 2708–2711. https://doi.org/10.1149/1.2059184.
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Bradke, M. V., W. Schnurnberger i I. Seybold. "Surface microstructure on Raney nickel catalysts". Proceedings, annual meeting, Electron Microscopy Society of America 48, nr 4 (sierpień 1990): 272–73. http://dx.doi.org/10.1017/s0424820100174497.
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Raney nickel is a favorite electrocatalyst for alkaline water electrolysis and fuel cells. The good electrochemical properties of this material result from its very fine porosity giving the electrodes a large effective surface. Usually the microstructure is formed by chemical etching of a nickel alloy, leaving back a highly porous electrode consisting of nearly pure nickel. It is well known that the total effective surface can considerably vary depending on the etching process, but up to now the understanding of the influence of all etching parameters on the resulting pore structure is quite ambiguous. Consequently, the study of the microporosity on Raney nickel is an important task within the scope of the development of electrocatalytic electrodes.
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Aboukhater, Aya, Mohammad Abu Haija, Fawzi Banat, Israa Othman, Muhammad Ashraf Sabri i Bharath Govindan. "Ni(1−x)Pdx Alloyed Nanostructures for Electrocatalytic Conversion of Furfural into Fuels". Catalysts 13, nr 2 (23.01.2023): 260. http://dx.doi.org/10.3390/catal13020260.
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A continuous electrocatalytic reactor offers a promising method for producing fuels and value-added chemicals via electrocatalytic hydrogenation of biomass-derived compounds. However, such processes require a better understanding of the impact of different types of active electrodes and reaction conditions on electrocatalytic biomass conversion and product selectivity. In this work, Ni1−xPdx (x = 0.25, 0.20, and 0.15) alloyed nanostructures were synthesized as heterogeneous catalysts for the electrocatalytic conversion of furfural. Various analytical tools, including XRD, SEM, EDS, and TEM, were used to characterize the Ni1−xPdx catalysts. The alloyed catalysts, with varying Ni to Pd ratios, showed a superior electrocatalytic activity of over 65% for furfural conversion after 4.5 h of reaction. In addition, various experimental parameters on the furfural conversion reactions, including electrolyte pH, furfural (FF) concentration, reaction time, and applied potential, were investigated to tune the hydrogenated products. The results indicated that the production of 2-methylfuran as a primary product (S = 29.78% after 1 h), using Ni0.85Pd0.15 electrocatalyst, was attributed to the incorporation of palladium and thus the promotion of water-assisted proton transfer processes. Results obtained from this study provide evidence that alloying a common catalyst, such as Ni with small amounts of Pd metal, can significantly enhance its electrocatalytic activity and selectivity.
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Sonkar, Piyush Kumar, Vellaichamy Ganesan i Vijay Rao. "Electrocatalytic Oxidation and Determination of Cysteine at Oxovanadium(IV) Salen Coated Electrodes". International Journal of Electrochemistry 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/316254.
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A transition metal complex, oxovanadium(IV) salen (where salen representsN,N′-bis(salicylidene)ethylenediamine) is immobilized on glassy carbon (GC) electrodes and utilized for electrocatalytic oxidation of cysteine. In presence of oxovanadium(IV) salen, increased oxidation current is observed due to the effective oxidation of cysteine by the electrogenerated oxovanadium(V) salen species. The oxidation current linearly varies with the concentration of cysteine from 0.1 to 1.0 mM. The modified electrode has good sensitivity and low limit of detection. These properties make the oxovanadium(IV) salen as an effective electrocatalyst for the determination of cysteine.
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Milikić, Jadranka, Raisa C. P. Oliveira, Andres Tapia, Diogo M. F. Santos, Nikola Zdolšek, Tatjana Trtić-Petrović, Milan Vraneš i Biljana Šljukić. "Ionic Liquid-Derived Carbon-Supported Metal Electrocatalysts as Anodes in Direct Borohydride-Peroxide Fuel Cells". Catalysts 11, nr 5 (14.05.2021): 632. http://dx.doi.org/10.3390/catal11050632.
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Three different carbon-supported metal (gold, platinum, nickel) nanoparticle (M/c-IL) electrocatalysts are prepared by template-free carbonization of the corresponding ionic liquids, namely [Hmim][AuCl4], [Hmim]2[PtCl4], and [C16mim]2[NiCl4], as confirmed by X-ray diffraction analysis, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy and Raman spectroscopy. The electrochemical investigation of borohydride oxidation reaction (BOR) at the three electrocatalysts by cyclic voltammetry reveals different behavior for each material. BOR is found to be a first-order reaction at the three electrocatalysts, with an apparent activation energy of 10.6 and 13.8 kJ mol−1 for Pt/c-IL and Au/c-IL electrocatalysts, respectively. A number of exchanged electrons of 5.0, 2.4, and 2.0 is obtained for BOR at Pt/c-IL, Au/c-IL, and Ni/c-IL electrodes, respectively. Direct borohydride-peroxide fuel cell (DBPFC) tests done at temperatures in the 25–65 °C range show ca. four times higher power density when using a Pt/c-IL anode than with an Au/c-IL anode. Peak power densities of 40.6 and 120.5 mW cm−2 are achieved at 25 and 65 °C, respectively, for DBPFC with a Pt/c-IL anode electrocatalyst.
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Aladeemy, Saba A., Abdullah M. Al-Mayouf, Maged N. Shaddad, Mabrook S. Amer, Nawier K. Almutairi, Mohamed A. Ghanem, Nouf H. Alotaibi i Prabhakarn Arunachalam. "Electrooxidation of Urea in Alkaline Solution Using Nickel Hydroxide Activated Carbon Paper Electrodeposited from DMSO Solution". Catalysts 11, nr 1 (13.01.2021): 102. http://dx.doi.org/10.3390/catal11010102.
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Electrooxidation of urea plays a substantial role in the elimination of urea-containing wastewater and industrial urea. Here, we report the electrodeposition of nickel hydroxide catalyst on commercial carbon paper (CP) electrodes from dimethyl sulphoxide solvent (Ni(OH)2-DMSO/CP) for urea electrooxidation under alkaline conditions. The physicochemical features of Ni(OH)2-DMSO/CP catalysts using scanning electron microscopy and X-ray photoelectron spectroscopy revealed that the Ni(OH)2-DMSO/CP catalyst shows nanoparticle features, with loading of <1 wt%. The cyclic voltammetry and electrochemical impedance spectroscopy revealed that the Ni(OH)2-DMSO/CP electrode has a urea oxidation onset potential of 0.33 V vs. Ag/AgCl and superior electrocatalytic performance, which is a more than 2-fold higher activity in comparison with the counterpart Ni(OH)2 catalyst prepared from the aqueous electrolyte. As expected, the enhancement in electrocatalytic activity towards urea was associated with the superficial enrichment in the electrochemically active surface area of the Ni(OH)2-DMSO/CP electrodes. The results might be a promising way to activate commercial carbon paper with efficient transition metal electrocatalysts, for urea electrooxidation uses in sustainable energy systems, and for relieving water contamination.
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Bu, Yingping, Yawen Zhang, Yingying Liu, Simin Li, Yanlin Zhou, Xuefen Lin, Zicong Dong, Renchun Zhang, Jingchao Zhang i Daojun Zhang. "MOF-Derived Urchin-like Co9S8-Ni3S2 Composites on Ni Foam as Efficient Self-Supported Electrocatalysts for Oxygen Evolution Reaction". Batteries 9, nr 1 (7.01.2023): 46. http://dx.doi.org/10.3390/batteries9010046.
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Effective and inexpensive electrocatalysts are significant to improve the performance of oxygen evolution reaction. Facing the bottleneck of slow kinetics of oxygen evolution reaction, it is highly desirable to design the electrocatalyst with high activity, good conductivity, and satisfactory stability. In this work, nickel foam supported hierarchical Co9S8–Ni3S2 composite hollow microspheres were derived from in situ-generative MOF precursors and the subsequent sulfurization process by a simple two-step solvothermal method. The composite microspheres were directly grown on nickel foam without any binder, and nickel foam was used as the nickel source and support material. The morphology and constitution of the series self-supported electrodes were characterized by SEM, TEM, XRD, XPS, and Raman, respectively. The unique porous architecture enriched the electrode with sufficient active surface and helped to reactants and bubble evolved during electrochemical water oxidation. Through tuning the concentration of cobalt source and ligand, the content ratio of Co9S8 and Ni3S2 can be modulated. The heterostructures not only afford active interfaces between the phases but also allow electronic transfer between Co9S8 and Ni3S2. The optimized Co9S8-Ni3S2/NF-0.6 electrode with the highest electrochemical surface area and conductivity shows the best OER performance among the series electrodes in 1 M KOH solution. The overpotential of Co9S8-Ni3S2/NF-0.6 is only 233 mV when the current density is 10 mA cm−2, and corresponding Tafel slope is 116.75 mV dec−1. In addition, the current density of Co9S8-Ni3S2/NF-0.6 electrocatalyst hardly decreased during the 12 h stability measurement. Our approach in this work may provide the future rational design and synthesis of satisfactory OER electrocatalysts.
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Jin, Song. "(Invited) Efficient and Selective Electrocatalytic and Photoelectrochemical Conversion of Energy and Chemicals". ECS Meeting Abstracts MA2022-02, nr 48 (9.10.2022): 1811. http://dx.doi.org/10.1149/ma2022-02481811mtgabs.
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Due to the intermittent nature of most renewable energy sources (such as solar and wind), practical large scale renewable energy utilization demands both efficient energy conversion and large scale energy storage or alternative usage. Earth-abundant but highly active and selective electrocatalysts are needed to enable efficient and sustainable production of fuels and chemicals using electrocatalytic and photoelectrochemical (PEC) energy conversion. We developed earth-abundant electrocatalysts for highly efficient hydrogen evolution reaction (HER) and oxygen evolution (OER). We recently combined computations and experiments to develop metal compounds as selective catalysts for two-electron oxygen reduction reaction (2e- ORR) to produce hydrogen peroxide (H2O2) and the subsequent electro-Fenton process for upgrading biomass molecules. We have integrated these earth-abundant electrocatalysts with efficient semiconductor materials to demonstrate efficient photoelectrochemical hydrogen generation systems. We also developed high performance hybrid solar-charged storage devices that integrate photoelectrochemical solar cells and redox flow batteries (RFBs). In these integrated solar flow batteries (SFBs), solar energy is absorbed by semiconductor electrodes to directly charge up the redox couples without external electric bias. Such charged redox molecules can then be either discharged to generate the electricity when needed or used to produce fuels and chemicals.