Enhanced visible light photocatalytic activity of ZnIn2S4 modified by semiconductors

Abstract

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.