One-pot synthesis of graphene-wrapped NiSe^sub 2^-Ni^sub 0.85^Se hollow microspheres as superior and stable electrocatalyst for hydrogen evolution reaction

A novel porous electrocatalyst of reduced graphene oxide (RGO)-wrapped NiSe2-Ni0.85Se hollow microspheres (RNHM) has been synthesized via one-pot hydrothermal process, which is facile, cheap and easy to realize scalable manufacture. Compared to bare NiSe2, Ni0.85Se and NiSe2-Ni0.85Se hollow microspheres (NHM), RNHM shows outstanding hydrogen evolution properties with a low Tafel slope value of 31.3 mV dec−1, a low onset potential of −175 mV (vs RHE), and a high cathode current density of 37 mA cm−2 (at ∼ −240 mV vs RHE). More importantly, it shows excellent HER stability after 2000 CV cycles. That superior performs of RNHM can be attributed to the well-designed hollow microsphere architecture with rich porosity and high specific surface area, which provides abundant active sites for HER. In addition, the two-dimensional graphene nanosheets can not only act as a highly conductive matrix facilitating the charge transfer during the process of HER, but also work as a flexible skeleton guaranteeing excellent structural stability. This study provides a novel and rational architecture design strategy of Pt-free catalysts with superior performances and outstanding stability for hydrogen evolution reaction.