Bioinspired proton relay on amino-functionalized PdCe metallene accelerates hydrogen oxidation kinetics and CO exclusion.

Inspired by [FeFe]-hydrogenases, a polyaniline-functionalized PdCe metallene mimics the enzyme's secondary coordination sphere, achieving triple synergy that weakens H* binding, relays protons via -NH- groups, and shields against CO. The catalyst surpasses Pt/C in HOR kinetics with only 1.2% activity loss under 100 ppm CO, establishing secondary-sphere engineering as a paradigm for CO-immune Pt-free HOR catalysts.