Enhanced visible light photocatalytic activity of ZnIn2S4 modified by semiconductors

To improve the visible light photocatalytic activity of a ZnIn2S4 sample, we synthesized two kinds of coupled-photocatalysts: TiO2@ZnIn2S4 core–shell type heterostructure composites by a simple and flexible hydrothermal route using TiO2 as the precursor and CuO/ZnIn2S4 contact type heterostructure composites incorporated with different amounts of CuO by the impregnation–calcination method. These as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Visible absorption spectra (UV-Vis) and nitrogen adsorption measurements. An enhancement in photocatalytic activity was observed after the addition of TiO2 and CuO. It was found that the as-synthesized TiO2@ZnIn2S4 photocatalyst was more efficient than TiO2 and ZnIn2S4 in the photocatalytic degradation of methylene blue (MB). TEM images confirmed that the TiO2@ZnIn2S4 nanoparticles possessed a well-proportioned core–shell morphology. On the other hand, the effects of CuO loading amount on the crystal structure, and photocatalytic properties of CuO/ZnIn2S4 samples for MB degradation under visible light irradiation were investigated, suggesting that the introduction of CuO could influence the morphology and BET specific surface area of the ZnIn2S4 sample and enhance the visible light absorption of photocatalysts. The photocatalytic degradation performance of MB was remarkably improved in the presence of CuO/ZnIn2S4 compared to pure ZnIn2S4 and 10 mol% CuO/ZnIn2S4 was found to possess the optimal photocatalytic performance. Moreover, mechanisms for the enhanced photocatalytic activity of the TiO2@ZnIn2S4 and CuO/ZnIn2S4 composites were proposed.