NiPS3 Nanosheet-Graphene Composites as Highly Efficient Electrocatalysts for Oxygen Evolution Reaction

Developing new electrocatalysts is essentially important for efficient water splitting to produce hydrogen. Two-dimensional (2D) materials provide great potential for high-performance electrocatalysts because of their high specific surface area, abundant active edges, and tunable electronic structure. Here, we report few-layer NiPS3 nanosheet-graphene composites for high-performance electrocatalysts for oxygen evolution reaction (OER). The pure NiPS3 nanosheets show an overpotential of 343 mV for a current density of 10 mA cm(-2), which is comparable to that for IrO2 and RuO2 catalysts. More importantly, the NiPS3 nanosheet-graphene composites show significantly improved OER activity due to the synergistic effect. The optimized composite shows a very low overpotential of 294 mV for a current density of 10 mA cm(-2), 351 mV for a current density of 100 mA cm(-2), a small Tafel slope of 42.6 mV dec(-1), and excellent stability. These overall performances are far better than those of the reported 2D materials and even better than those of many traditional materials even at a much lower mass loading of NiPS3.