Work Function‐Driven Synthesis of Electron Deficient Ruthenium‐Copper Cluster on Oxygenated Carbon for Pure‐Water Electrolysis

Ruthenium is a promising alkaline water splitting cathode due to its fast water dissociation kinetics and cost‐effectiveness. However, its excessively strong binding affinity for reaction intermediates severely hampers catalytic efficiency. To address this challenge, we demonstrate a work‐function‐engineered synthesis of sub‐2 nm ruthenium‐copper clusters hosted on oxygen‐rich carbon via a ligand‐driven spontaneous reduction pathway. Electrochemical measurements and theoretical calculations reveal that copper incorporation and strong coupling with oxygen‐containing moieties induce electron‐deficient states at Ru sites. The electronic modulation optimizes the adsorption energy of reactant intermediates, ultimately accelerating water dissociation and hydrogen desorption kinetics. Consequently, the catalyst delivers a high turnover frequency of 16.3 s −1 at an overpotential of 100 mV, representing a 5.8‐fold improvement over the benchmark platinum catalyst. When integrated into a pure water‐fed anion exchange membrane water electrolyzer, it achieves 1.8 A cm −2 at 2.0 V and operates stably for 840 h at 0.5 A cm −2 .