ZnO–graphene composite for photocatalytic degradation of methylene blue dye

A series of ZnO and graphene composites (ZnO/GRs) was synthesized by a simple and nontoxic hydrothermal reaction route. The TEM, AFM, FTIR, Raman and current–voltage (I–V) results demonstrated that the ZnO particles were coated by the graphene sheets, confirming the formation of ZnO/GRs composites. During the photocatalytic test, in comparison with ZnO and P25, the ZnO/GRs exhibited enhanced photocatalytic performance for degradation of methylene blue (MB) dye since the graphene sheets could prevent the photoinduced hole–electron pairs of ZnO from recombination by transferring the photoinduced electron to the MB. When the mass ratio of ZnO to graphene was 50:1, the ZnO/GR showed the best photocatalytic performance. Moreover the photocorrosion of ZnO was inhibited to a large extent, which could be attributed to the formation of ZnO and graphene composite.

► ZnO/graphene composites were synthesized by a nontoxic hydrothermal reaction route.
► ZnO/GRs exhibited better photocatalytic performance for degrading MB dye.
► The optimized mass ratio for best photocatalytic performance is 50:1.
► The photocorrosion of ZnO was inhibited to a large extent in ZnO/GRs.