Stabilizing Cobalt Sites with d10-Configured p-Block Cations for Iridium-Free Proton Exchange Membrane Water Electrolysis

Proton exchange membrane water electrolysis (PEMWE) requires anode catalysts that sustain acidic oxygen evolution in practical stacks with minimal noble-metal content. Cobalt spinel oxides are cost-attractive but dissolve rapidly in acid as cobalt sites over-oxidize under anodic bias. Here we show that incorporation of d10-configured p-block cations (Sb, Ge, In, and Ga) into Co3O4 stabilizes cobalt sites by promoting robust heterometallic Co–O–M interactions. Density functional theory predicts dopant-driven charge redistribution that suppresses over-oxidation of octahedral Co while maintaining favorable binding of oxygen intermediates. Operando Co K-edge X-ray absorption and time-resolved dissolution measurements confirm reduced oxidation-state dynamics and cobalt loss, whereas a d-block d10 control (Zn) shows no such stabilization. In a PEMWE single cell at 80 °C, Sb/Co3O4 reaches >3500 mA cm–2 at 2.0 V and operates for >1000 h at 250 mA cm–2. This work establishes p-block d10 incorporation as a general route to iridium-free PEMWE anodes.