Effect Of Semiconductor Conduction Band On The Photocatalytic Property Of Ag@AgX/Semiconductor Composite

The use of solar photocatalytic technology has become an important way to solve the global environmental and resource issues, and to find stable and efficient photocatalyst has become an important issue. In this work, we chose the n-type semiconductor ZnO, oxygen doped O-C₃N₄ and p-type semiconductor Fe₂TiO₅ to study this effect, and prepared ZnO/Ag@AgCl, O-C₃N₄/Ag@AgCl and Fe₂TiO₅/Ag@AgCl composites by composite with Ag@AgCl, respectively. Then studied their photocatalytic property by photocatalytic degradation test of Rhodamine B under visible light, the results showed that the rate of degradation decreased in descending order of ZnO/Ag@AgCl > O-C₃N₄/Ag@AgCl > Fe₂TiO₅/Ag@AgCl. Further analysis showed the possible reason might be as follows. ZnO and O-C₃N₄ are both n-type semiconductors, the conduction band potential of O-C₃N₄ being more negative than that of ZnO. The electrons in Ag@AgCl is therefore more easily transferred to ZnO, the conduction band of which has a larger difference with Ag@AgCl, thus resulting in the higher separation efficiency of photo-generated electron-hole and better photocatalytic properties of ZnO/Ag@AgCl composite. Fe₂TiO₅ is a p-type semiconductor, the conduction band potential of which is very close to ZnO, but when Fe₂TiO₅ composites with Ag@AgCl, a built-in electric field is formed at their interface, preventing the diffusion of the photo-generated electrons, so the photocatalytic performance is relatively poor. The comparative results show that for the semiconductors with same conduction band potential but different types, when compositing with Ag@AgCl, the n-type semiconductor is easier to receive photogenerated electrons than the p-type semiconductor, promoting photo-generated electron- hole separation efficiency, so as to show better photocatalytic and photoelectrochemical properties.