Degradation Kinetics during Oxygen Electrocatalysis on Perovskite-Based Surfaces in Alkaline Media

The oxygen evolution reaction (OER) during alkaline water electrolysis is the bottleneck of water splitting. Perovskite materials have been particularly proposed as good and economically reasonable electrocatalysts for the OER, showing promise and advantages with respect to classic metallic electrodes. However, the degradation of perovskites during catalysis limits their service lifetime. Recently, the material BaCo_0.98Ti_0.02O_3-δ:Co₃O₄ was shown to be electrocatalytically and chemically stable during water electrolysis even under industrially relevant conditions. The lifetime of this perovskite-based system is prolonged by a factor of 10 in comparison to that of Pr_0.2Ba_0.8CoO_3-δ and is comparable to that of industrially applied electrodes. Here we report on the degradation kinetics of several OER catalysts at room temperature, comparatively studied by monitoring the oxygen evolution at microelectrodes. A decrease in the reaction rate within a maximum of 60 s is observed, which is related to chemical and/or structural changes at the oxide surface.