Chlorine-Induced Surface Reconstruction of Perovskite Oxide Boosts Oxygen Evolution Reaction Activity

Chlorine-doped perovskite oxides were synthesized as efficient electrocatalysts for the oxygen evolution reaction (OER) in an alkaline medium. The introduction of chloride ions into the perovskite lattice via doping increased oxygen vacancies and altered the cobalt valence state in PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF). Among the compositions tested, PrBa0.5Sr0.5Co1.5Fe0.5O4.7+δCl0.3 (PBSCFCl0.3) exhibited the best OER performance, with a low overpotential of 330 mV at 10 mA cm–2 and a Tafel slope of 69 mV dec–1. Detailed characterizations revealed changes in the perovskite crystal structure, oxidation states, and oxygen defects as a result of chlorine doping. Electrocatalytic testing indicated the PBSCFCl0.3 maintained high activity and stability for over 100 h. The enhanced OER kinetics is attributed to chlorine leaching from the lattice, causing surface reconstruction and hydroxide formation, which accelerates proton transfer. This work demonstrates chlorine-doping as an effective approach to tune perovskite properties and promote oxygen electrocatalysis through defect engineering and surface chemical effects.