Influence of Oxygen Evolution during Water Oxidation on the Surface of Perovskite Oxide Catalysts

Perovskites such as Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF82) can be highly active for the oxygen evolution reaction (OER) upon water oxidation in alkaline solution. Here we report that BSCF82 can quickly undergo amorphization of its surface at OER potentials, which is accompanied by reduced surface concentrations of Ba2+ and Sr2+ ions as well as increased pseudocapacitive and OER currents. Such quick amorphization during OER was also observed for perovskite catalysts with similar OER activities such as Ba0.5Sr0.5Co0.4Fe0.6O3−δ and SrCo0.8Fe0.2O3−δ. In contrast, perovskite oxides with lower OER activities than BSCF82 did not undergo this transformation when subjected to identical electrochemical conditions. These…