Template-free synthesis of hollow Ni/reduced graphene oxide composite for efficient H2 evolution

To resolve the energy crisis and environment pollution, it is urgent to exploit highly efficient and inexpensive catalysts for the hydrogen evolution reaction (HER). Herein, we report a hollow Ni/RGO (reduced graphene oxide) composite (HNG) as an efficient HER catalyst, which was fabricated through a facile template-free method using graphene oxide (GO) sol as the raw material. The explosively released gases from GO under thermal treatment restrained the growth of Ni species towards the formed gas bubbles, resulting in the formation of hollow Ni nanoparticles (NPs). The hollow structure contributes to the diffusion of the reactant H2O to the active sites for HER. The electrocatalytic HER activity of HNG increases with the amount of hollow Ni NPs in the range from 3 to 12 wt% Ni loading. However, the dye-sensitized photocatalytic H-2 evolution activity reaches the maximum at 9.0 wt%, due to the interaction between the dye and RGO. Under optimal conditions, the highest apparent quantum yield (AQY) for the hydrogen evolution at 470 nm reaches 47.7%. This study paves the way for the synthesis of various hollow metal-RGO materials.