Elucidating mechanism of Se-induced lattice oxygen activation and structural stability in perovskite oxide for oxygen evolution catalysis

Abstract

Perovskite oxides (ABO3) are promising candidates for oxygen evolution reaction (OER) catalysts due to mixed ionic-electronic conductivity, structural flexibility, and tailorable properties. However, most perovskite oxides have inherent barriers of low catalytic activity and poor electrochemical stability. Here, Se doping is utilized as a strategy to improve the OER activity and stability of perovskite. Se doping not only increases the electrical conductivity, which also enhances the catalytic performance, but also induces the formation of oxygen vacancies, which serve the active sites where OER occurs via the lattice oxygen mechanism (LOM). Density functional theory (DFT) calculations reveal that Se doping contributes to the formation of oxygen non-bonding states (ONB) due to lower electronegativity of Se than O, which increases the overlap between O 2p and B-site metal d-bands, provided a buffer that protects M − O framework from oxidative degradation, and activates lattice oxygen toward OER via LOM pathway. The Ba2+ leaching is suppressed by the steric hindrance of Se2− and inhibition of O2− diffusion from bulk to the surface, preventing the collapse of the perovskite structure. Therefore, this research presents a novel method to enhance the activity and stability of perovskite OER catalysts and elucidates the mechanism of improved activity and stability.