Dual Modulation of Hydroxyl Action on Ruthenium Surface by Single‐Atom Supports for Alkaline H2 Evolution

Abstract Ruthenium (Ru)‐based catalysts are known to accelerate the slow kinetics of the alkaline hydrogen evolution reaction (HER). However, enhancing the transfer kinetics of adsorbed hydroxyl (OH ad ) remains challenging. Herein, a dual‐regulation strategy is presented to alleviate OH blockage on the catalyst surface, using a cluster‐level Ru electrocatalyst supported by single‐atom CoN 4 generated in situ on carbon nanotubes (CNTs). Experimental and theoretical studies demonstrate that introducing oxophilic single‐atom CoN 4 can mitigate the strong interaction between Ru and OH ad by directly competing for OH ad on the Ru surface, thereby preventing Ru site poisoning. Meanwhile, single‐atom CoN 4 effectively modifies the electronic structure of Ru atomic clusters (ACs), indirectly optimizing the energy barriers for OH desorption at the Ru interface and promoting OH ad release. The electronic interaction between Ru ACs and CoN 4 also inhibits Ru atom migration, significantly enhancing catalytic stability. The resulting catalyst shows excellent HER activity at 10 mA cm −2 with a low overpotential of 15 mV in alkaline solution and remains stable at 200 mA cm −2 for over 1000 h. An alkaline anion‐exchange membrane water electrolyzer (AEMWE) using this catalyst can exhibit an ultralow potential (1.785 V at 1 A·cm −2 ) and high stability at 500 mA·cm −2 .