Superdispersed NiCo2S4 nanoparticles anchored on reduced graphene oxide for efficient hydrogen evolution reaction in acidic and alkaline media

Reasonable design and preparation of the earth abundant and efficient electrocatalysts for hydrogen production from the electrolysis of water is an effective solution to solve the growing global energy and environmental crisis. Herein, in order to increase the number of the active sites and fasten the charge transfer of NiCo2S4, a facile two-step solvothermal method is used to prepare superdispersed NiCo2S4 nanoparticles anchored on reduced graphene oxide (NCS/rGO) as low-cost and high-efficient electrocatalyst for hydrogen evolution reaction (HER). By modulating the amount of rGO, the as-prepared NCS/rGO composite shows high specific surface area of 114.4 m2 g-1 and small particle size of 50-60 nm, which exhibits excellent HER activity with a lower overpotential of 115 mV at 10 mA cm-2 and a smaller charge transfer resistance of 12 omega in acidic solution. Additionally, in the case of alkaline solution, the as-prepared NCS/rGO composite also exhibits a low overpotential of 241 mV and a small Tafel slope of 110 mV dec-1. The significantly improved HER performance of NCS/rGO composite can be ascribed to the constructed heterogeneous interface between NiCo2S4 nanoparticles and rGO, which can inhibit the aggregation of NiCo2S4 nanoparticles and enhance the intrinsic electrical conductivity. In light of the excellent HER electrocatalytic performance, the inexpensive NCS/rGO composite might be regarded as a promising alternative in HER and other energy conversion and storage applications.