Preparation of FeCoNiMoCu High-Entropy Alloy Thin Film Electrode and Its Water Splitting Performance

High-entropy alloy (HEA) thin films have attracted considerable attention owing to their multi-element synergistic effects, high stability, tunable electronic structure, and low-cost potential. In this study, an FeCoNiMoCu HEA thin-film electrode was successfully fabricated via coating and vacuum sintering techniques, using equiatomic Fe, Co, Ni, Mo, and Cu powders as precursors. The crystal structure, surface morphology, elemental composition/distribution, and chemical states of the FeCoNiMoCu HEA thin-film electrode were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS), respectively. The hydrogen evolution reaction (HER) performance of the electrode was evaluated in four different electrolyte systems. Additionally, the influence of electrolyte temperature on HER activity was investigated, with the corresponding activation energy (Ea) calculated for each tested system. Results demonstrate that the FeCoNiMoCu HEA thin-film electrode exhibits outstanding HER performance across multiple electrolyte systems. Compared with conventional HER catalysts, this FeCoNiMoCu thin-film electrode achieves a balance between high catalytic activity and broad electrolyte compatibility, filling the research gap in HEA thin-film catalysts with superior performance in various complex electrolyte environments and providing a new reference for the development of low-cost, high-stability HER catalysts for practical applications.