Facile Aqueous Synthesis of High-Entropy Metal Sulfides for Sulfion Oxidation-Assisted Energy-Saving Hydrogen Production

The high energy consumption of water electrolysis is primarily limited by the sluggish oxygen evolution reaction (OER). Replacing the OER with thermodynamically favorable anodic reactions provides an effective strategy to improve energy efficiency. Among these reactions, the sulfide oxidation reaction (SOR) offers both low thermodynamic potential and environmental relevance. In this work, we develop a high-entropy metal sulfide catalyst, CuNiCoFeMnS, via a facile aqueous synthesis route, achieving homogeneous elemental dispersion and a highly disordered structure. The catalyst exhibits excellent SOR activity, delivering a low potential of 0.396 V to achieve a current density of 10 mA cm−2. In addition, it enables a significant reduction of 1.05 V in cell voltage at 50 mA cm−2 compared with conventional water electrolysis. Furthermore, by integrating solar energy, the system enables simultaneous upgrading of sulfide-containing wastewater and energy-efficient hydrogen production. These results demonstrate a promising pathway toward coupling waste remediation with sustainable hydrogen generation.