Boron‐Tuned Covalency Enables Durable and High‐Performance Perovskite OER Catalysts

ABSTRACT Perovskite catalysts show great promise for the oxygen evolution reaction (OER) but still face challenges in activity and stability. Here, we report boron incorporation into Sr ₂ (FeCo _0.6 Mo _0.4 )O _5+δ to tailor the Co–O–Fe covalency and electronic states, delivering 300 mV at 10 mA cm ^{− 2} and a 67 mV dec ^{− 1} Tafel slope with > 140 h durability in 1 m KOH. Spectroscopy shows lowered Co/Fe valences and an increased fraction of lattice oxygen, while Density Functional Theory(DFT) (ELF/DOS/free‐energy) indicates strengthened Transition Metal‐Oxygen (TM─O) bonding and reduced reaction barriers. These findings support a shift toward an adsorbate evolution like pathway with suppressed lattice oxygen participation, rationalizing both the enhanced activity and robustness. Flexible Zn air batteries using Sr ₂ (FeCo _0.6 Mo _0.4 ) _0.9 B _0.1 O _5+δ exhibit lower charging overpotentials and superior cycling stability than Pt/C+RuO ₂ , highlighting device relevance. This work establishes metalloid doping enabled covalency engineering as a general strategy to boost OER performance and stability in perovskites.