Tailored water–surface interactions on cobalt oxide for stable proton-exchange-membrane water electrolysis

Developing Earth-abundant anode electrocatalysts for proton-exchange-membrane water electrolysis (PEMWE) to replace iridium is crucial for reducing hydrogen production costs but their poor acid stability remains a major challenge. Here we prepare a lanthanum and calcium co-doped Co 3 O 4 catalyst, which can tune water–surface interactions to suppress cobalt dissolution, thereby enhancing stability. Lanthanum with weak water affinity is introduced onto the Co 3 O 4 surface to construct atomic sites with specific water–molecule interactions (CoLa-SWMI). The CoLa-SWMI reconstructs the interfacial water environment and moderately alleviates the polarization of the metal–oxygen bond induced by hydrogen bonding with water molecules, thereby extending catalyst lifetime. Moreover, the leaching of surface calcium species creates highly active coordinatively unsaturated cobalt sites, which enhance catalytic activity (CoLaCa-SWMI). PEMWE using a CoLaCa-SWMI anode operates stably for 830 h at 1.0 A cm −2 . This study provides an approach to designing non-noble-metal electrocatalysts, potentially reducing reliance on rare metals in PEMWE.