Solid-state synthesis of ZnS/graphene nanocomposites with enhanced photocatalytic activity

• ZnS/graphene nanocomposites was synthesized by low-temperature solid-state method.
• Effects of synthetic conditions on photocatalytic activity were investigated.
• ZnS/graphene nanocomposites assisted by NaBH4 showed excellent catalytic activity.
• O2− was proved to be the main reactive species for the degradation of MO.

A simple solid-state method was employed for the first time to obtain ZnS/graphene nanocomposites. The chemical composition, morphology and properties of the products were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, nitrogen absorption-desorption and UV–vis spectroscopy. The photocatalytic performances of the products were evaluated by methyl orange. The results indicated that nanocomposites exhibited superior photocatalytic activity to pure ZnS, owing to the reduction of photoinduced electron–hole pair recombination induced by the introduction of graphene. In addition, effects of solid-state synthetic conditions on photoactivity were also investigated. It was found that the nanocomposite obtained by the reduction of NaBH4 exhibited higher photoactivity than that of got by the direct addition of graphene, which can be attributed to the high specific surface area and the enhanced synergetic effect between ZnS and graphene. With the help of scavengers, ·O2- was proved to be the main reactive species during the degradation.