Facilitating Dissociation–Diffusion–Desorption Process over Ru Nanoclusters Engineering hcp-Ni₃Fe for Hydrogen Evolution at High Current Densities

Developing efficient electrocatalysts toward hydrogen evolution at high current densities still remains challenging. Engineering metastable phase alloy catalysts represents a promising strategy for enhancing electrocatalytic performance through modulating electronic states. Herein, the epitaxial growth of Ru clusters on hexagonal closed-packed Ni3Fe alloy supported on Ni foam (hcp-Ru/Ni3Fe/NF) has been realized by coupling galvanic replacement and room-temperature CH4 plasma. This catalyst achieves low overpotentials of 58 and 145 mV at 100 and 500 mA cm–2, respectively, toward alkaline hydrogen evolution. When integrated into an anion-exchange membrane water-splitting electrolyzer (AEMWE), it delivers a cell potential of 1.95 V at 1000 mA cm–2. Theoretical calculations confirm that hcp-Ni3Fe facilitates H2O adsorption and activation and rapid dissociation, while Ru introduction lowers H* adsorption energy, accelerating H* diffusion and desorption, thereby achieving a dissociation–diffusion–desorption mechanism. This work advances the development of metastable electrocatalysts for industrial green hydrogen production.