High-Entropy FeCoCuNiMo Selenide Electrocatalysts with Tunable Selenization for Efficient Hydrogen Evolution in Alkaline Media

Efficient and stable electrocatalysts are essential for accelerating the hydrogen evolution reaction (HER) in alkaline water electrolysis. Herein, a self-supported FeCoCuNiMo high-entropy selenide electrocatalyst was fabricated on nickel–molybdenum foam via hydrothermal precursor growth followed by controllable gas-phase selenization. By tuning the selenization temperature and duration, the phase composition and degree of selenization were systematically regulated. Structural characterization indicated that the optimized FCCNMSe-450–3 electrode formed a highly selenized diselenide phase with pronounced lattice distortion originating from the high-entropy configuration. In 1.0 M KOH, FCCNMSe-450–3 required an overpotential of 174.3 mV to reach 100 mA cm–2 and maintained a stable operation for more than 150 h. Electrochemical analyses suggested that the enhanced HER performance arose from the synergistic effects of multimetal components, lattice distortion, and the favorable electronic structure of the diselenide phase. These findings highlighted the importance of controllable selenization in tuning the structure and catalytic behavior of high-entropy selenide electrocatalysts for alkaline hydrogen evolution.