Local Oxygen Vacancy‐Mediated Oxygen Exchange for Active and Durable Acidic Water Oxidation

Abstract Developing an active and durable acidic oxygen evolution reaction (OER) catalyst is vital for implementing a proton exchange membrane water electrolyzer (PEMWE) in sustainable hydrogen production. However, it remains dauntingly challenging to balance high activity and long‐term stability under harsh acidic and oxidizing conditions. Herein, through developing the universal rare‐earth participated pyrolysis‐leaching approach, we customized the active and long lifespan pseudo‐amorphous IrO x with locally ordered rutile IrO 2 and unique defect sites (IrO x ‐3Nd). IrO x ‐3Nd achieved a low overpotential of 206 mV and long‐term durability of 2200 h with a slow degradation rate of 0.009 mV h −1 at 10 mA cm −2 , and, more importantly, high efficiency in PEMWE (1.68 V at 1 A cm −2 for 1000 h) for practical hydrogen production. Utilizing in situ characterizations and theoretical calculations, we found that lattice oxygen vacancies (O v ) and contracted Ir‐O in locally ordered rutile IrO 2 induced the O v ‐modulated lattice oxygen exchange process, wherein thermodynamically spontaneous occupation of surface hydroxyl groups on O v and effective promotion of O─O coupling and lattice oxygen recovery accounted for enhanced activity and durability. This work underscores the importance of tailor‐made local configuration in boosting activity and durability of OER catalyst and different insights into the promotion mechanism.