Self-assembled CuCo2S4 nanosheets with rich surface Co3+ as efficient electrocatalysts for oxygen evolution reaction

Abstract Eminent OER electrocatalysts occupies a vital position for hydrogen produced from water splitting. Up to now, sulfides with spinel structure have been considered as the most promising electrocatalysts to replace noble metal catalysts, but generally their catalytic activities are still unsatisfactory. Based on above situation, we used one-step solvothermal method to synthesis two CuCo2S4 nanosheets by introducing two different surfactants. Two CuCo2S4 nanosheets both show outstanding catalytic properties for OER. Specifically, CuCo2S4 CNS exhibits the best OER performance with a low overpotential of 269 mV at a current density of 10 mA cm−2 and a small Tafel slope of about 41 mV dec−1 in 1.0 M KOH. The CV scanning and chronoamperometry tests also show its excellent stability. XPS analysis reveals the introduction of Cu ions into Co3S4 lattice improve the relative concentration of Co3+ on CuCo2S4 nanosheets surface, which makes the catalytic performance get extensively improvement.