The Optical And Electric Properties Of CdS/ZnO Nano-composites

With the improvement of industrial and economic, environmental problem is increasingly serious. Photocatalytic technology is the most effective way to solve this problem. Semiconductor photocatalyst has much advantage, such as simple operation, wide appliance and so fotrh. Therefore, it is payed more attention. Currently, as photocatalyst, TiO2 is the most widely used by researcher, but TiO2 is an indirect band-gap semiconductor with low probability of electronic transition, result to a slower reaction rate in the photocatalytic process. Compared with TiO2, ZnO is a direct band gap semiconductor with high probability of electronic transition, there are much more oxygen vacancies on the surface and electrons are more easily trapped in ZnO, thereby, photocatalytic activity is o. But as a wide gap semiconductor, the range of light absportion is confined to ultraviolet light. Therefore, extended the region of light absportion from ultraviolet to visible light is very helpful to enhance the photocatalytic activity. As we known, CdS is one of the most well-known visible-light-driven photocatalysts. However, powdery CdS is prone to photocorrosion in the photocatalytic reaction where CdS itself is oxidized by the photogenerated holes. Many efforts have been carried out to improve the stability of metal sulfides, for example, by loading the noble metal (Pt) on the surface of CdS, incorporating the nanoparticles of metal sulfides into the interlayer photocatalysts, etc. The band gap of CdS is narrow than that of ZnO, fabricated ZnO/CdS nano-composites by surface modification of CdS nanoparticles can extend the region of light from from ultraviolet to visible light, it is greatly beneficial to improve the photocatalytic activity.In this work, a sample hydrothermal process is proposed for the fabrication of a CdS/ZnO nano-composites. The as-grown CdS/ZnO heterostructures were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and photoluminescence (PL). Study on the change of photocatalytic activity of ZnO after the surface modification of CdS nanoparticles, and also compare the photocatalytic activity between ZnO nanorods/CdS nanoparticles composites and ZnO nanobelts/CdS nanoparticles composites. The results reveal that, the photocatalytic activity of ZnO/CdS nano-composites is advanced than pure ZnO. And compared with ZnO nanorods/CdS nanoparticles composites, the photocatalytic activity of ZnO nanobelts/CdS nanoparticles composites is obviously enhanced. Furthermore, we select ZnO/CdS nano-composites as photocatalyst and sense microelectrode simultaneously to decompose organics and sensing the process of photocatalysis.