Facile Synthesis of Ag/TiO2 by Photoreduction Method and Its Degradation Activity of Methylene Blue under UV and Visible Light Irradiation

Abstract

A series of Ag/TiO2 with various Ag contents were prepared by photoreduction method. Commercial TiO2 from Evonik-Degussa was used as the catalyst. Ag was used as the cocatalyst. This facial synthesis method is cheap and easy. TiO2 was suspended in water with various concentrations of silver nitrate. The solution was illuminated by UV light for 36 h. Ag would deposit on the surface of TiO2. This method can deposit all Ag cation in the starting material on TiO2 after 36 h irradiation by UV light. X-ray diffraction, high resolution-TEM, and X-ray photoelectron spectroscopy were used to characterize the surface, morphology and chemical composition of the catalysts. Photocatalytic degradation of methylene blue in water on these catalysts was carried out under UV and visible light irradiation, respectively. The methylene blue concentration in water was measured by a UV-vis spectrophotometer. The results showed that the bulk structure of TiO2 did not change and some of Ag was incorporated into the surface of TiO2 lattice. The change in the electronic state of Ti on surface is attributed to the replacement of titanium atoms by silver atoms on the TiO2 surface structure which induced visible light response and enhanced the photocatalytic activity. 1 wt% Ag is the optimum loading to have high activity.