Stabilizing Cobalt Sites with d10-Configured p-Block Cations for Iridium-Free Proton Exchange Membrane Water Electrolysis
Jaehyuk Shim, Sungeun Heo, Hee Jung Kwon, Kangmin Suh, Hyunsoo Ahn, Yun Do Kim, Sihwa Lee, Seungwook Baek, Hosung Choi, Seongbeom Lee, Junghwan Jang, Kug-Seung Lee, Taeghwan Hyeon, Byoung-Hoon Lee, Minho Kim, Yung-Eun SungAbstract
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.