Boosted Oxygen Evolution on Iridium through Dual‐Interface‐Diffusion Generated Oxygen Vacancies in Supporting Tungsten Oxide

Abstract For oxygen evolution reaction (OER) in proton exchange membrane water electrolyzer (PEMWE), iridium (Ir) remains the primary active component in catalysts, but its high cost and low utilization efficiency pose significant barriers to large‐scale deployment. Designing high‐performance supported Ir‐based catalysts is of urgent necessity. By constructing a hierarchical WO₃@TiN supporting material, an Ir/WO₃@TiN catalyst is designed with superior OER activity and stability. The optimized Ir/WO₃@TiN catalyst exhibits mass activity (MA) up to 920.93 mA mg_Ir⁻¹, over 20 times that of commercial IrO₂. Experimental evidences confirm the facilitated oxygen vacancies induced by the diffusion of Ti and Ir at the interfaces. The membrane electrode assembly (MEA) fabricated with the Ir/WO₃@TiN anode catalyst (0.3 mg_Ir cm⁻²) can operate at 1.0 A cm⁻² with merely 1.60 V (70 °C), with durable operation for over 200 h. Theoretical calculations reveal that the doping of Ti and Ir atoms in WO₃ lattice promotes formation of oxygen vacancy, which can optimize the surface electronic structure on Ir and lower the energy barrier of *OOH formation, leading to the boosted OER activity. This work not only introduces new strategies for support design but also shows their great potential for practical applications.