Oxophilic Gallium Single-Atom Regulating Micropore-Confined Os Atomic Clusters Enables Efficient Alkaline Hydrogen Electrocatalysis.

Rational design of cost-effective atomic cluster (AC) catalysts with high mass activity and robust durability remains a formidable challenge for alkaline hydrogen-energy conversion, owing to intrinsic aggregation of ACs, difficulty in decoupling the adsorption energetics of hydrogen- and oxygen-containing intermediates, and acute CO poisoning. Herein, we report the synthesis of a class of electrocatalysts using carbon-micropore confinement with adjacent isolated oxophilic Ga sites to stabilize Os ACs and decouple these conflicting interfacial adsorption demands. We demonstrate that carbon aerogel micropores kinetically lock ultrasmall Os clusters against migration and coalescence, while Ga sites polarize spatially proximate Os clusters through support-mediated charge redistribution, downshifting the Os d-band center and weakening H* and CO* binding. Meanwhile, Lewis-acidic oxophilic Ga centers capture and activate H2O/OH* species, establishing an oxygenated-intermediate relay that lowers the barrier for the sluggish Volmer step. Os AC/Ga1@pCA delivers exceptional mass activities for hydrogen evolution (2185.5 A gOs -1 at 100 mV) and hydrogen oxidation (7.29 A mgOs -1 at 50 mV), together with outstanding CO tolerance. In an anion-exchange-membrane water-electrolyzer, it achieves a PGM-price-normalized activity of 370.7 A dollar-1 at 1.8 V and operates stably at 500 mA cm-2 for over 300 h with a degradation rate of mere ∼48.6 µV h-1.