Rapid microwave-assisted syntheses of reduced graphene oxide (RGO)/ZnIn2S4 microspheres as superior noble-metal-free photocatalyst for hydrogen evolutions under visible light

A rapid microwave-assisted method has been developed for the preparations of flower-like RGO/ZnIn2S4 microspheres which are consisted of interwoven nanosheets of ZnIn2S4 and RGO. The as-prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The mechanism for the formation of the flower-like microspheres of RGO/ZnIn2S4 nanocomposites via the microwave-assisted method has been proposed. As compared with the samples obtained solvothermally, the RGO/ZnIn2S4 microspheres obtained via the microwave-assisted method show highly enhanced photocatalytic performance for hydrogen evolution under visible light irradiations, due to the existence of strong interaction between ZnIn2S4 and RGO. The highest hydrogen evolution rate (132.3 mu mol h(-1)), observed over an optimum RGO loading amount of 1.0 wt%, is comparable to that over 1.0 wt%-Pt/ZnIn2S4 (129.0 mu mol h(-1)). This work demonstrates the important role played by microwave heating in the preparations of RGO-based materials. The results also highlight the potential of using RGO as a non-noble metal cocatalyst in the photocatlaytic hydrogen evolution process. (C) 2014 Elsevier B.V. All rights reserved.