Effect of oxygenation on electrocatalysis of La0.6Ca0.4CoO3−x in bifunctional air electrode |
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Authors: | Nae-Lih Wu Wei-Ren Liu Sern-Jei Su |
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Affiliation: | Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan, People's Republic of China |
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Abstract: | A vacuum-annealed La0.6Ca0.4CoO3−x was consecutively oxygenated in air at temperatures decreasing from 800 to 100 °C, and its electrocatalytic activities for oxygen reduction and evolution were then measured as a function of the oxygenation temperature. The valence of Co cation, changing between +2 and +3, was found susceptible to annealing either in vacuum or air. The catalytic activities initially decrease monotonically as the oxygenation temperature was decreased from 800 to 300 °C, as a result of increasing oxygen content, and then rise abruptly with the oxygen reduction activity reaching a maximum at 200 °C and the oxidation activity at 150 °C. X-ray photoelectron spectroscopy analysis indicated that the enhancements by the low-temperature oxygenation involved increased OH coverage and less charged cations at surface. The results clearly reveal the importance of the post-calcination annealing process for optimizing the performance of La0.6Ca0.4CoO3−x in air electrode applications. |
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Keywords: | Zinc-air battery Perovskite oxide Air electrode Cathodic catalyst Oxygen vacancy |
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