Rare Earth‐Induced CoO₆ Octahedral Distortion in Perovskite: An Efficient Catalytic Platform for RuO₂‐Catalyzed Water Oxidation

Abstract Rare earth (RE)‐based perovskites are considered as promising platform for oxygen evolution reaction (OER) due to their low cost and tunable structures. However, the systematic synthesis of perovskite catalysts with satisfactory performance has rarely been reported. Herein, a general synthetic protocol for RE‐substituted LaCoO₃ (RE‐LCO) perovskites is demonstrated. Particularly, after loaded with RuO₂, the as‐prepared RuO₂:0.2Ce‐LCO hybrid structures exhibit OER performance with a low overpotential of 135 mV at 10 mA cm⁻² in 1.0 m KOH, together with remarkable long‐term operation, representing one of the most efficient and robust Ru‐based catalysts. Comprehensive experimental results indicate that the enhanced OER mechanism is attributed to the Ce‐substitution, which alters the geometric configuration of CoO₆ octahedra and generates more oxygen vacancies. Furthermore, the robust interaction between Ce‐LCO and RuO₂ stabilizes the valence state of Ru site. Theoretical calculations corroborate that Co 3d orbitals overlap with Ce 4f orbitals near the Fermi level, greatly improving the electron transfer between Co and Ce atoms.