Locking the adsorbate-evolution pathway against lattice-oxygen participation via Mn/Mo co-doping of IrRuO_x for ultrastable acidic oxygen evolution at high current densities

Proton exchange membrane water electrolysis requires highly active and ultrastable oxygen evolution reaction (OER) catalysts that can operate at high current densities for long periods to lower hydrogen production cost, but the scarcity of iridium (Ir) and instability of ruthenium (Ru) remain critical bottlenecks. Here, we report a dual-dopant strategy to simultaneously regulate activity and durability by incorporating acid-stable manganese (Mn) and molybdenum (Mo) into IrRu mixed oxides. The resulting IrRuMn_0.05Mo_0.05O_x catalysts exhibit an overpotential of 230 mV at 10 mA cm^-2 and demonstrate outstanding long-term stability exceeding 5500 h. Differential electrochemical mass spectrometry reveals that the OER occurring on IrRuMn_0.05Mo_0.05O_x follows the adsorbate evolution mechanism even at high current densities up to 500 mA cm^-2 with negligible lattice-oxygen participation, preserving structural integrity under harsh conditions. Theoretical calculations reveal that Mn/Mo co-doping induces charge redistribution between Ir and Ru, lowering the energy barrier to O–O coupling while significantly increasing Ru dissolution energy. When integrated into membrane electrode assemblies, IrRuMn_0.05Mo_0.05O_x delivers a cell voltage of 1.77 V at 3.0 A cm^-2. Significantly, the cell operates at 3.0 A cm^-2 for 5200 h with minimal decay, making IrRuMn_0.05Mo_0.05O_x hold great promise as an efficient and durable OER catalyst for practical applications.