Spontaneous Oxygen Reduction on Perovskite Oxide Surface in Aqueous Medium

Abstract

Oxygen reduction/evolution reactions (OER/ORR) do not normally occur spontaneously at room temperature. Here, we will demonstrate that a perovskite oxide can drive a spontaneous ORR in aqueous media. Our experiments show that spontaneous ORR, while taking place at open-circuit conditions, results in a severe oxidation of the surface and causes cation leaching, oxygen intercalation and gradual dissolution of the perovskite. Using DFT and molecular dynamics simulations of the perovskite-electrolyte system, we propose a possible mechanism for this highly unusual phenomenon. Likely, a spontaneous ORR is connected with the emergence of a specific atomic configuration at the surface that stabilizes reaction intermediates and reduces activation barrier(s) for the ORR.