Non-Lattice Oxygen Triggered Deprotonation via Discontinuous Amorphous Interlayer on Supported IrO_x for Acidic Oxygen Evolution

Iridium-based catalysts for the acidic oxygen evolution reaction (OER) predominantly follow the adsorbate evolution mechanism (AEM), with their intrinsic activity limited by sluggish proton-transfer kinetics. Based on this, a strategy is proposed involving the construction of a discontinuous WO_x interlayer incorporating isolated W single atoms and amorphous WO_x clusters on supported Ir-based catalysts. The optimized Ir/W-TiN catalyst achieves current densities of 100 mA cm⁻² at remarkably low overpotentials of 293 mV. Leveraging the non-lattice oxygen from the amorphous WO_x, this design promotes a shift in the reaction pathway from the conventional AEM to an interface non-lattice oxygen-assisted deprotonation mechanism (IOADM), simultaneously enhancing both activity and stability. The incorporation of W species facilitates the formation of oxygen vacancies and a hydrogen-bond network, which lowers the reaction energy barrier and accelerates deprotonation kinetics. In a proton exchange membrane water electrolyzer, the membrane electrode assembly with the Ir/W-TiN anode exhibits a high current density exceeding 2.2 A cm⁻² at 1.8 V. Furthermore, with a low Ir loading of 0.2 mgIr cm⁻², it demonstrates excellent durability, maintaining stable operation for 2000 h at 1.0 A cm⁻². This work provides new mechanistic insights for designing highly efficient, stable, and low-Ir-loaded anode catalysts via interface engineering.