Multi-site Relay Catalysts with Regulating Intrinsic Activity of each Functional Site for Efficient Hydrogen Evolution Reaction.

Ruthenium is emerging as a promising catalyst for the hydrogen evolution reaction (HER) in alkaline water electrolysis. However, the high energy barrier for water dissociation and inappropriate hydrogen adsorption energy often hinders their catalytic efficiency. To address these challenges, Ru-Fe7C3@CNF with abundant twin boundaries has been rationally designed based on synergistic relay catalysis principles. Experimental results combined with mechanistic analysis demonstrate that the electron-deficient Fe7C3 can accelerate water dissociation, and the resulting protons can rapidly spill over to Ru due to a smaller work function difference, subsequently, the Ru with moderate ΔGH* facilitates hydrogen evolution. Notably, Ru-Fe7C3@CNF with twin-boundary defects and charge redistribution induced by the heterointerface optimizes the adsorption energy and enhances the intrinsic activity of each functional site. As expected, this catalyst exhibits enhanced HER performance that is superior to commercial Pt/C. Moreover, the assembled anion exchange membrane water electrolysis utilizing Ru-Fe7C3@CNF//NiFe LDH operates at a voltage of 1.67 V at a current density of 0.5 A cm- 2 and maintains remarkable stability over 300 h. This work offers a valuable strategy for the rational design of multisite electrocatalysts.