Rapidly reconstructed CuCo2S4@Co–V–O–F nanocatalysts for efficient and stable overall water splitting in alkaline and seawater electrolysis

Abstract

The strategic construction of bifunctional electrocatalytic electrodes integrating high activity and exceptional durability is critical for sustainable hydrogen generation through water and seawater splitting. Addressing challenges including sluggish reaction kinetics and chloride-induced corrosion in marine electrolyzers remains imperative. Mixed transition metal oxides/sulfides, particularly cobalt–vanadium-based composites, demonstrate superior electrocatalytic properties owing to their tunable electronic configurations, multivalent redox states, enhanced charge transfer capabilities, and abundant exposed active sites. Here, we have prepared CuCo₂S₄@Co–V–O–F. The electrode material is then calcined under argon protection, and a synergistic structural engineering and surface treatment adjustment strategy is adopted to construct nanostructures. The optimized catalyst exhibits remarkable bifunctional performance: low HER overpotentials of 87.8 mV (1 M KOH) and 95.5 mV (alkaline seawater) at −10 mA cm⁻², coupled with OER overpotentials of 227.3 mV and 213.5 mV, respectively. Notably, the symmetric electrolyzer assembled with these nanowire arrays achieves an ultralow cell voltage of 1.796 V at 50 mA cm⁻², demonstrating exceptional efficiency for overall water splitting while maintaining robust stability in corrosive saline media.