The effects of ZnO morphology on photocatalytic efficiency of ZnO/RGO nanocomposites

ZnO/RGO nanocomposites with different morphologies, including RGO/ZnO nanoparticles, RGO/ZnO nanosheets, RGO/ZnO nanospheres and RGO/ZnO nanorods were prepared through hydrothermal process, characterized by XRD, TEM, SEM, UV-vis spectra, electrochemical analysis, and tested in photocatalytic hydrogen production. It was found that the ZnO morphologies have great influence on photo absorption, separation efficiency of photo-generated charges and photocatalytic performance of ZnO/RGO nanocomposites. RGO/ZnO nanorods with a sandwich-like 3D structure, consisting of ZnO nanorods grown vertically on both sides of graphene sheets exhibited a highest photocatalytic H-2 production rate of 610, which is about 1.1 times, 1.9 times and 2.6 times more active than ZnO/RGO particles, ZnO/RGO nanospheres and ZnO/RGO nanosheets, respectively. The results of PL, CV curves and photocurrent measurements show that the superior photocatalytic performances of RGO/ZnO nanorods and RGO/ZnO nanoparticles originate from the higher transfer rate of photo-generated electron from ZnO to RGO, and repressed recombination of the photoinduced hole-electron pairs of ZnO, which is closely related with the morphology of ZnO and the strength of chemical interaction between ZnO and RGO. (C) 2015 Elsevier B.V. All rights reserved.