Decoupling Water Dissociation and Hydrogen Adsorption via the Dual-Site Synergy of Spatially Coupled V Single Atoms and Ni5 Clusters for Efficient Alkaline Hydrogen Evolution Reaction

Efficient electrocatalysts for the alkaline hydrogen evolution reaction (HER) are critical to sustainable energy conversion, yet their performance is severely hampered by sluggish water dissociation kinetics. Herein, we design a synergistic catalyst in which V single atoms and Ni5 clusters are coanchored on N-doped graphene, enabling highly efficient alkaline HER. Density functional theory calculations uncover a distinctive dual-site mechanism: the Ni5 cluster acts as the active center for water dissociation, significantly reducing the energy barrier, while the adjacent V single atom introduces a unique bridge site for hydrogen adsorption at the V–Ni5 interface, thereby optimizing the hydrogen adsorption free energy (ΔGH*). This spatial coupling of V single atoms and Ni5 clusters cooperatively accelerates both water dissociation and hydrogen adsorption. The present findings establish a precise multiactive-site design principle, providing new theoretical insights to guide the development of high-performance alkaline HER electrocatalysts.