ZnS-CdS-TaON nanocomposites with enhanced stability and photocatalytic hydrogen evolution activity

In recent years, tantalum oxynitride (TaON) semiconductor as one of the most efficient photocatalysts has been studied intensively owing to the appropriate potentials for overall solar water splitting. In this work, ZnS/CdS/-TaON composite photocatalysts with wide light response were successfully prepared by nitridation of Ta2O5 at 800 degrees C in a wet NH3 flowing and subsequently deposition CdS and ZnS quantum dots. The powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis diffuse reflection spectroscopy (DRS), N-2 adsorption-desorption isothermals, X-ray photoelectron spectroscopy (XPS), and so on. The photocatalytic property for hydrogen production was also studied. The results indicated that CdS and ZnS quantum dots with a diameter of 3-8nm were uniformly dispersed on the surface of -TaON, which enlarged the spectral response of the ZnS/CdS/-TaON photocatalysts. And the optimized H-2 evolution rate of ZnS/CdS/-TaON composite (839.6molh(-1)g(-1)) is about 14 times higher than that of CdS/-TaON in the absence of any noble-metal cocatalyst and 47 times higher than that of Pt loaded -TaON sample. The enhanced photocatalytic activity is attributed to the higher separation efficiency of electrons and holes with the heterogeneous junction between ZnS, CdS, and -TaON. Besides, the presence of -TaON and ZnS also prevent the photocorrosion of CdS. The results provide a new insight for developing the TaON-based nanocomposite photocatalysts with enhanced stability and excellent photocatalytic H-2 production activity. [GRAPHICS] . HighlightsZnS/CdS/-TaON nanocomposite photocatalysts had been successfully fabricated though deposition of CdS and ZnS quantum dots over -TaON nanoparticles.CdS and ZnS/CdS significantly improve the photocatalytic activity of -TaON.The optimized H2 evolution rate of ZnS/CdS/-TaON composite is about 14 times higher than that of CdS/-TaON in the absence of any noble metal cocatalyst and 47 times higher than that of Pt loaded -TaON sample.The band structures and the possible transfer mechanism were proposed.