Highly active and stable bi-functional NiCoO2 catalyst for oxygen reduction and oxygen evolution reactions in alkaline medium |
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| Affiliation: | 1. Department of Mechanical and Industrial Engineering, Qatar;2. Department of Chemical Engineering, Qatar University, P O Box 2713, Doha, Qatar;3. Qatar Environment and Energy Research Institute (QEERI), Hamad Bin Khalifa University, Qatar Foundation, PO Box 34110, Doha, Qatar;1. Department of Chemistry, School of Science, Tianjin University, China;2. Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China;1. Department of Chemistry, Bar-Ilan Institute for Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat-Gan, 5290002, Israel;2. Department of Biological Chemistry, Ariel University, Ariel, 40700, Israel;3. Electrochemical Energy Laboratory, Department of Chemistry, SRM Institute of Science and Technology, Kattankulathur 603203, India;1. Department of Applied Chemistry, School of Science, State Key Laboratory for Mechanical Behavior of Materials, Xi''an Jiaotong University, Xi''an 710049, China;2. Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS, UK;3. Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL 60439, USA;4. Materials Science and Engineering, Department of Applied Physics and Applied Mathematics, Columbia University, NY 10027, USA;1. School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, 212013, PR China;2. School of Pharmacy, Jiangsu University, Zhenjiang, 212013, PR China;3. Jiangsu Institute of Scientific and Technical Information, China |
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| Abstract: | Single step solution combustion technique was used to synthesize NiO, Co3O4 and NiCoO2 mixed metal oxide with good crystallinity and uniform properties. XRD spectrum indicates the existence of cubic NiCoO2 phase without any impurities. SEM results indicate the presence of porous structures in all the three cases, a typical characteristic of combustion synthesized samples, which is due to the evolution of gases during the synthesis process. TEM along with the phase mapping shows the presence of well dispersed elements Ni, Co and O throughout the sample. All the three catalysts were evaluated for their bifunctionality towards oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline medium. NiCoO2 shows the highest number of electron transfer in the overall reaction mechanism with the maximum kinetic current density of 12.3 mA/cm2. The kinetics of NiCoO2 towards ORR and OER was analyzed using Tafel plot and compared with the mono-metal oxides. The catalytic stability was evaluated for 24 h using continuous chronoamperometric (CA) runs, where NiCoO2 shows exceptionally stable performance without any significant decay in current. The highest activity of NiCoO2 could be due to the presence of higher oxidation states of Ni and Co and because of the existence of the oxygen defects acting as active sites for the oxygen adsorption/desorption during the electrocatalytic reactions. Based on the activity and stability trends, NiCoO2 is found to be a promising bifunctional oxygen electrocatalyst for long-term applications. |
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| Keywords: | Mixed oxides Oxygen reduction reaction Oxygen evolution reaction |
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