Engineering Ru nanoclusters onto Ni₃S₂/Co₂P heterointerface for enhanced alkaline hydrogen evolution

Ru-based catalysts are considered as promising hydrogen evolution catalysts. However, they exhibit low activity and stability due to their high water-splitting energy barrier and dissolution of Ru active sites under relatively harsh conditions. Herein, we report an interface engineering strategy to construct a “interfacial bridge” by embedding metallic Ru nanoclusters at the Ni₃S₂/Co₂P heterointerface. Experimental and theoretical calculations demonstrate that the introduction of Ru nanoclusters induces charge rearrangement and optimizes the adsorption energies of reaction intermediates (*OH and H*) on the active sites. Meanwhile, Ru is chemically confined at the heterointerface through the formation of Ru-S and Ru-P bonds with Ni₃S₂ and Co₂P, respectively, which suppresses its dissolution during the electrochemical reaction. Furthermore, the rod-like Ni₃S₂ on the surface physically confines the Ru nanoclusters onto the Co₂P surface, analogous to the soil-fixing effect of tree roots, thereby further enhancing the stability of the material. In 1 M KOH, Ru-Ni₃S₂/Co₂P exhibits excellent HER performance and stability, requiring only 24.5 mV and 81.4 mV to achieve current densities of 10 and 100 mA cm⁻², respectively, with stable operation exceeding 200 h at the both current densities.