Hexagonal NiMoO4-MoS2 nanosheet heterostructure as a bifunctional electrocatalyst for urea oxidation assisted overall water electrolysis

Abstract

For overall water splitting, easy synthesis methodologies for non-precious metal bifunctional electrocatalysts with the advantages of low cost and high activity are essential. Herein, a hexagonal NiMoO₄-MoS₂ nanosheet heterostructure on nickel foam (NiMoO₄-MoS₂/NF) was synthesized by simple hydrothermal and annealing treatment. Synergies between NiMoO₄ and MoS₂ significantly promoted the intrinsic activity of the HER and exposed more active sites for the UOR and the HER. The NiMoO₄-MoS₂/NF electrocatalyst shows small electric potentials of 1.345 V for the UOR and 23 mV for the HER in 1.0 M KOH with 0.5 M urea at 10 mA cm⁻². NiMoO₄-MoS₂/NF has outstanding overall water splitting performance, with a low cell voltage of 1.445 V at 10 mA cm⁻² and an excellent sustainability of 24 h. The bifunctional electrocatalyst's design strategy and controllable synthesis of the hexagonal NiMoO₄-MoS₂ nanosheet heterostructure will benefit the overall urea water separation efficiency.