Dual Modulation of Interfacial Water Structure and Metal-Support Interaction via Single-Atom Sites for Industrial Hydrogen Evolution.

Ru-based catalysts are promising cathodes for alkaline hydrogen evolution reaction (HER) in anion exchange membrane water electrolysis (AEMWE), yet sluggish water dissociation, overly strong Ru─H adsorption, and durability loss still limit their practical performance. Herein, we construct a controlled M─N─C (M═Fe, Co, Ni) support series for anchoring Ru particles and establish a dual-regulation strategy that couples interfacial water activation with support-induced Ru electronic optimization. M─N4 coordination motifs mainly regulate the near-surface water environment and promote water-dissociation kinetics, while the M─N─C supports modulate the electronic structure of Ru through metal-support interaction. The optimized Ru/Ni─N─C delivers an ultralow overpotential of 9 mV at 10 mA cm-2 and achieves 4000 mA cm-2 at 2.0 V in a practical AEMWE, with an apparent voltage increase rate of 3.1 µV h-1 over 1600 h. In situ Raman and infrared spectroscopies reveal that Ni─N4 motifs enrich and polarize interfacial K+-H2O species, facilitating the Volmer step. Theoretical calculations further show that Ni─N4 lowers the water dissociation barrier to 0.19 eV, while the Ni─N─C support optimizes Ru─H adsorption to -0.07 eV through metal-support interaction. This work provides mechanistic guidance for designing efficient Ru-based alkaline HER catalysts by integrating water-structure regulation with support-mediated Ru electronic modulation.