Making Ternary‐Metal Hydroxysulfide Catalyst via Cathodic Reconstruction with Ion Regulation for Industrial‐Level Hydrogen Generation

Abstract Deep insight into electrochemical reconstruction aids in the decoding of electrocatalytic mechanisms and the development of design principles for advanced catalysts. Despite recent achievements, research concerning cathodic reconstruction is still lacking compared to the anodic variety. This work captures the electroreductive reconstruction dynamics over bimetal Ni–Mo sulfide by various in/ex situ techniques, and whereby cathodic reconstruction is steered with ion regulation to achieve a heterogeneous Ni–Mo–Fe ternary metal hydroxysulfide (NMFSOH) as a robust hydrogen‐evolving catalyst that is competent in industrial‐level water electrolysis. The thermodynamically adaptive heterosynergism in the resultant NMFSOH catalyst can coordinate water dissociation and hydrogenation for the alkaline hydrogen evolution reaction even at high current densities. A flow‐type alkaline water electrolyzer with dual NMFSOH electrodes affords an electricity consumption of 3.99 kW h Nm⁻³ and an electricity‐to‐hydrogen efficiency of 88.7%, manifesting its competitive cost‐effectiveness toward practical applications. This study showcases ion‐regulatory reconstruction as an effective strategy to construct high‐performance electrocatalysts.