Preparation of ZnO/ZnSe Nanostructures and Their Photocatalytic Properties Under Visible Light Irradiation

Homogeneous ZnO/ZnSe nanostructure photocatalytic materials with diameters of 500 nm were successfully prepared by a pyrohydrolytic method in which ZnO nanospheres with diameters of 600 nm were used as sacrificial templates. In order to compare the effect of different O/Se ratios on photocatalytic properties, ZnO/ZnSe nanostructures with different degrees of selenylation were obtained by keeping other reaction parameters unchanged and adjusting the amount of hydrazine hydrate. The structures and morphologies of pure ZnO and ZnO/ZnSe nanostructures were investigated by field emission scanning electron microscopy (SEM) and X-ray diffraction(XRD). And their photocatalytic activities were investigated by degradation of methylene blue(MB) solution. The results indicate that ZnO/ZnSe nanostructures show wider absorption bands in the visible region as well as in the UV region and exhibit superior photocatalytic performance compared with pure ZnO. This is mainly attributed to narrow-band ZnSe, which could effectively absorb visible light and make electrons excited. Photoexcited electrons could be transferred to the conduction band of ZnO under the power of diffusion potential, while the holes remain in the ZnSe valence band, which facilitates charge separation of electron-hole pair, decreases recombination probability, and thus improves the photocatalytic efficiency.