Impedance measurements in different alkaline solutions on an oxygen-evolving La0.5Sr0.5CoO3 electrode |
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Authors: | H Willems M Moers GHJ Broers JHW De Wit |
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Institution: | State University of Utrecht, Inorganic Chemistry Department, Croesestraat 77A, 3522 AD Utrecht The Netherlands |
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Abstract: | It was found that the oxygen evolution reaction on La0.5Sr0.5CoO3 in strong alkaline solutions has a Tafel slope of ~ 60 mV/dec and a reaction order at constant overpotential with respect to the KOH activity of 0.6–0.8. From impedance measurements differential Tafel slopes were calculated and were found to be ~ 60 mV/dec at overpontentials > 250 mV. Effective capacitances having a broad maximum at an overpotential of about 200 mV in all alkaline solutions were calculated. The effective capacitance increased with increasing KOH concentration. Furthermore, the material decomposed at the surface when exposed to strong oxygen evolution. From the results a modified Krasil'shchikov reaction path is analysed. |
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