Facilitating\nDissociation–Diffusion–Desorption\nProcess over Ru Nanoclusters Engineering hcp-Ni<sub>3</sub>Fe for\nHydrogen Evolution at High Current Densities

Developing efficient electrocatalysts toward hydrogen\nevolution\nat high current densities still remains challenging. Engineering metastable\nphase alloy catalysts represents a promising strategy for enhancing\nelectrocatalytic performance through modulating electronic states.\nHerein, the epitaxial growth of Ru clusters on hexagonal closed-packed\nNi<sub>3</sub>Fe alloy supported on Ni foam (hcp-Ru/Ni<sub>3</sub>Fe/NF) has been realized by coupling galvanic replacement and room-temperature\nCH<sub>4</sub> plasma. This catalyst achieves low overpotentials of\n58 and 145 mV at 100 and 500 mA cm<sup>–2</sup>, respectively,\ntoward alkaline hydrogen evolution. When integrated into an anion-exchange\nmembrane water-splitting electrolyzer (AEMWE), it delivers a cell\npotential of 1.95 V at 1000 mA cm<sup>–2</sup>. Theoretical\ncalculations confirm that hcp-Ni<sub>3</sub>Fe facilitates H<sub>2</sub>O adsorption and activation and rapid dissociation, while Ru introduction\nlowers H* adsorption energy, accelerating H* diffusion and desorption,\nthereby achieving a dissociation–diffusion–desorption\nmechanism. This work advances the development of metastable electrocatalysts\nfor industrial green hydrogen production.