Oxidation-resistant AgRuIr alloy nanocages for efficient and enduring oxygen evolution in proton exchange membrane...

The global transition to a hydrogen economy relies on efficient and durable catalysts for the oxygen evolution reaction within proton exchange membrane water electrolysis. Conventional metal oxide catalysts, particularly RuO₂, suffer from overoxidation and corrosion under acidic and high-potential conditions, limiting operational lifetime. Here we report a metallic catalyst composed of metastable AgRuIr alloy nanocages that challenge the prevailing view that metallic materials are unsuitable for this reaction. Mechanistically, the filled d orbitals of Ag reduce the oxophilicity of the alloy, weakening oxygen adsorption and preventing oxygen incorporation into the metal lattice. As a result, the nanocages exhibit higher activity than Ru/Ir oxides while maintaining a metallic state at high potentials, thereby fundamentally suppressing overoxidation. In a water electrolysis cell, the catalyst delivers 1 A cm^-2 at a cell voltage of 1.73 V and operates stably for 1500 hours with negligible voltage increase (0.93 μV h^-1) and minimal metal dissolution (0.5-0.7% kh^-1). These results redefine the potential of metallic catalysts for oxygen evolution in proton exchange membrane water electrolysis systems toward large-scale hydrogen production.