Activating P2-NaxCoO2 for efficient water oxidation catalysis via controlled chemical oxidation |
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| Authors: | B Li T Wang X Li X Zheng X Wu J Zhu H Xu |
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| Affiliation: | 1. CAS Key Laboratory of Soft Matter Chemistry, School of Chemistry and Materials Science, University of Science and Technology of China Hefei, Anhui 230026, China;2. National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, China;3. Department of Materials Science and Engineering, CAS Key Laboratory of Materials for Energy Conversion, CAS Center for Excellence in Nanoscience, University of Science and Technology of China, Hefei, Anhui 230026, China |
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| Abstract: | Electrocatalytic water oxidation is critically important for a wide range of emerging energy conversion devices. Co-based metal oxides are very promising candidates as high-performance oxygen evolution reaction (OER) catalysts. Here, it is shown that chemical oxidation of layered P2-NaxCoO2 could lead to compositionally tunable P2-NaxCoO2 with high OER activity. The optimal electrocatalytic activity emerges in a narrow range of sodium concentrations with Na0·28CoO2 exhibiting the lowest overpotential of 350 mV at 10 mA/cm2 and a Tafel slope of 29 mV/dec in 0.1 M NaOH electrolyte, outperforming the benchmark RuO2 catalyst and previous LiCoO2-based electrocatalysts. Electrochemical measurements and X-ray spectroscopic investigations reveal that chemically oxidized P2-NaxCoO2 catalysts are intrinsically active toward OER, arising from the abundant oxygen vacancies, increased Co-O covalency, and enhanced conductivity after deintercalation of the Na+. Our findings provide new insights into the design and synthesis of cost-effective catalysts toward efficient and durable OER. |
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| Keywords: | Cobalt Water oxidation Oxygen evolution reaction Chemical oxidation Electrocatalysis |
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