▎ 摘　　要

Exploiting new, low-cost and efficient electrocatalysts for hydrogen evolution reaction (HER) is important to resolve the energy crisis and environment pollution. In this work, graphene decorated with Ni nanoparticles (NPs) were synthesized via one-pot reduction using graphene oxide (GO, the obtained composite was denoted as GN) as a precursor. The as-prepared composite GN exhibits much better electrocatalytic and dye-sensitized HER activities than single Ni and reduced graphene oxide (RGO), namely, a great synergetic effect of RGO and Ni for HER. The coupling of metal Ni with the defect carbons of RGO plays a key role in the synergetic effect. The structure of GN composites is another key factor to the synergetic effect. The highest apparent quantum yield (AQY) for dyesensitized photocatalytic hydrogen evolution at 470 nm reaches 30.3% under the optimal conditions.