Modulating Iridium Electronic Structure With High-Valent Metal Doping for Efficient and Durable Acidic Oxygen Evolution Reaction

Developing efficient and robust catalysts for the acidic oxygen evolution reaction (OER) is crucial for advancing proton exchange membrane water electrolyzer (PEMWE). However, the benchmark iridium oxide (IrO₂) catalysts remain limited by their high cost and low activity under practical conditions. Herein, we report an iridium (Ir)-based heterostructured catalyst co-doped with high-valent tungsten (W) and molybdenum (Mo) atoms on a strongly coupled IrCuO_x/MnO₂ framework (W/Mo–IrCuO_x/MnO₂). Using a modified molten-salt method, W/Mo dopants are incorporated into IrCuO_x/MnO₂ nanosheets, leading to optimized electronic structure and enhanced active-site exposure. The resulting W/Mo–IrCuO_x/MnO₂ exhibits a low overpotential of 186 mV at 10 mA cm⁻² in 0.5 m H₂SO₄ and delivers a high mass activity of 1083 A g_Ir⁻¹. Remarkably, the catalyst exhibits exceptional durability, maintaining for 400 h at 50 mA cm⁻². Additionally, the nanosheet catalyst maintains long-term PEMWE performance (>500 h @ 1 A cm⁻² at 80°C). Operando spectroscopy and theoretical calculations reveal that co-doping high-valent W and Mo significantly enhances the Ir oxidation state and modulates Ir─O coordination at the W/Mo–IrCuO_x/MnO₂ interface, which generates optimized active sites and accelerates OER kinetics. These findings offer a promising strategy for designing high-performance, cost-effective OER catalysts for acidic water electrolysis.