Construction of an oxygen vacancy-enriched triple perovskite oxide electrocatalyst for efficient and stable oxygen evolution in acidic media†

The development of anodic electrocatalysts toward the oxygen evolution reaction (OER) in harsh acidic environments faces significant challenges of low efficiency, instability and high cost. Ru-based oxides exhibit remarkable initial activity toward the OER, but the presence of soluble high-valence oxygen-vacancy intermediates can accelerate the dissolution of Ru species. In this study, a triple Sr₂CaRu₂IrO₉ perovskite oxide electrocatalyst has been successfully synthesized, demonstrating a low overpotential of 172 mV at 10 mA cm⁻² and excellent stability for over 75 hours. The introduction of dual-site heteroatoms leads to the generation of oxygen vacancies, which control the excessive lattice oxygen participating in the OER via the lattice oxygen oxidation mechanism (LOM). This effectively prevents the excessive oxidation of Ru to form soluble Ru^>4+ species. Density functional theory (DFT) calculations show that the negative shift of O 2p and Ru 4d band centers weakens the covalency of Ru–O, optimizes the adsorption energy of oxygen intermediates, and thus improves the inherent catalytic activity and stability.