Urea-assisted enhanced electrocatalytic activity of MoS2-Ni3S2 for overall water splitting

The design and synthesis of non-precious metal-based bifunctional electrocatalysts with low cost and high performance for hydrogen and oxygen evolution in water are of great importance for renewable energy. Transition metal sulfides have attracted extensive interest owing to their easily adjustable electronic structures and rich chemical properties. Herein, the growth of MoS2–Ni3S2 on a nickel foam (MoS2–Ni3S2/NF) surface is investigated in the presence of urea, which can tune the morphology, surface electronic state and surface hydroxyl content of the product. The MoS2–Ni3S2/NF with optimal urea content shows remarkable electrocatalytic activity to hydrogen and oxygen evolution reactions with the corresponding overpotential at 100 mA cm−2 of only 181 mV and 355 mV, respectively. Upon using the product as a bifunctional electrocatalyst for overall water splitting, an overvoltage as low as 1.56 V is required and the stability is excellent for more than 80 000 s at 10 mA cm−2.