Durable Acidic Oxygen Evolution Via Self-Construction of Iridium Oxide/Iridium-Tantalum Oxide Bi-Layer Nanostructure with Dynamic Replenishment of Active Sites

• A self-constructed IrO2/IrTaOx bi-layer nanostructure, derived from an Ir–Ta metallic glass, achieves high-efficiency acidic OER with a mass activity of 1.06 A mgIr−1 at 300 mV overpotential, outperforming commercial Ir/C and IrO2 by 13.6 and 31.2 times, respectively. • The electronic interaction between Ir and Ta modulates the coordination environment of active Ir sites, preventing rapid oxidation to high-valence states and suppressing lattice oxygen participation, thereby enhancing both activity and stability. • The underlying amorphous IrTaOx layer dynamically replenishes depleted surface Ir sites via inward crystallization and selective dissolution, ensuring long-term durability under industrial-relevant current densities in acid. • This work provides a novel strategy for designing durable, low-Ir OER catalysts for PEM water electrolysis, addressing critical challenges of high noble metal loading and inadequate stability.