Anti‐Poisoning Tin Single‐Atom Unlocks High‐Activity Ruthenium Catalysts for Alkaline Hydrogen Evolution Reaction

The practical deployment of anion exchange membrane water electrolyzer (AEMWE) is constrained by the lack of efficient electrocatalysts for the alkaline hydrogen evolution reaction (HER), primarily due tothe sluggishVolmer step and inefficient intermediate desorption. While Ru‐based catalysts exhibit promising *H binding energy, their practical performance is compromised by poor water dissociation kinetics and susceptibility to active‐site blockage by adsorbed species. Herein, we report a Sn‐doped RuO 2 @Ru catalyst supported on carbon black, wherein atomically dispersed Sn modulates the electronic structure of RuO 2 via Sn─O bonds, simultaneously facilitating water dissociation, optimizing *H adsorption, and preventing *OH poisoning. The catalyst achieves exceptional performance with an overpotential of 9 mV at 10 mA cm −2 , positioning it among the most active HER catalysts reported to date. When integrated into a full AEMWE, it operates at 1.85 V and 1000 mA cm −2 with stability exceeding 300 h. Mechanistic studies suggest that Sn doping fine‐tunes the *OH and *H binding energies, addressing the kinetic imbalance inherent in conventional Ru catalysts. This work highlights the effectiveness of atomic‐level electronic engineering via an anti‐poisoning strategy for designing efficient, stable alkaline HER electrocatalysts toward industrial hydrogen production.