Self-Powered Water Electrolysis with Sulfide Waste as Consumable

Water electrolysis is a powerful and environmentally friendly strategy for green H2 production. However, the kinetics and efficiency of this process suffer seriously from the sluggish oxygen evolution reaction. Here, we report a fully self-powered H2 production approach coupling a hydrogen evolution reaction with a sulfide oxidation reaction. Driven by a sulfidic spent caustic stream, the lab-scale flow reactor can deliver an open-circuit voltage of up to 0.44 V and a self-powered current density of up to 33.79 mA cm–2. A hybrid NiCu-doped MoS2 catalyst is prepared using a nickel–copper etching waste fluid, which can effectively catalyze sulfide oxidation and hydrogen evolution. The conversion efficiencies for waste chemical energy to electricity and H2 are >40% and >30%, respectively. This work strongly suggests a self-powered H2 production potential and ability by coupling water splitting with small-molecule waste treatments, with substantial benefits concerning energy conservation, waste treatment, and resource optimization.