ZnO/ZnSe复合纳米结构的制备及可见光光催化性能

通过热水解法, 以氧化锌为模板, 成功制备出形貌均一的ZnO/ZnSe复合纳米结构. 为了对比不同O/Se比对光催化性能的影响, 保持其它反应参数不变, 调节还原剂水合肼的用量, 得到不同硒化程度的ZnO/ZnSe复合纳米结构. 采用场发射扫描电子显微镜、 X射线衍射仪和透射电子显微镜对样品的形貌及结构进行了表征, 通过测试该复合结构对亚甲基蓝的可见光催化降解评估了其光催化效率. 结果表明, 与纯ZnO比, ZnO/ZnSe复合结构在可见光区域和紫外光区域的光吸收范围变宽, 显示出较高的光催化效率. 原因在于ZnSe导带上的电子在扩散势能的作用下迁移到ZnO的导带上, 而空穴仍保留在ZnSe价带, 这样有助于光生电子和空穴对的分离, 降低其复合机率, 从而提高ZnO的光催化效率.

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.