Triadic Site‐Mediated Hydroxyl/Hydrogen Dual Spillover Effect to Boost Alkaline Hydrogen Evolution Reaction

Abstract Anion exchange membrane water electrolysis (AEMWE) operating at ampere‐level current densities is critical for sustainable hydrogen production. However, the sluggish kinetics of the multi‐step hydrogen evolution reaction (HER) drive substantial H*/OH* accumulation and active site blockage in catalysts. Herein, hydrogen/hydroxyl double spillover effect is induced to alleviate H*/OH* blockage in designing efficient catalysts, by linking Ru nanoparticles with oxophilic Nd‐Ru dual‐metal‐sites to create triadic active sites on N‐doped mesoporous carbon (RuNd‐NMC). The triadic sites collaboratively divide labor, in which Ru atoms in oxophilic Nd‐Ru dual‐metal‐sites facilitate water dissociation steps, while the Ru nanoparticles induce a unique hydrogen spillover effect of generated H* and the oxophilic Nd atoms triggers distinctive hydroxyl spillover effect of produced OH*. Such H*/OH* double spillover effect helps accelerate the transfer kinetics and avoid H*/OH* site poisoning in catalysts. As a result, RuNd‐NMC exhibits ultra‐low overpotential of 185 mV at 1 A cm −2 and 13.1‐fold increase of mass activity than Pt/C. In AEMWE, it can achieve an industrial‐scale current density of 1 A cm −2 at 1.74 V, and robust stability over 200 h@0.5 A cm −2 at 60 °C. This work offers fundamental insight into designing exceptional and ultrastable HER catalysts in AEMWE for high‐throughput hydrogen production.