Photocatalysis oxidation activity regulation of Ag/TiO2 composites evaluated by the selective oxidation of Rhodamine B

With the aid of TiO2 and Ag/TiO2 composites with ultrahigh specific surface areas (about 400 m2 g−1), we demonstrated a facile controlled strategy to adjust the photooxidation activity of Ag/TiO2 in the photocatalysis degradation process of Rhodamine B (RhB). A series of photocatalysis experiment results indicated that the selective oxidation of RhB could be performed through changing irradiation light. When the as-prepared unannealed Ag/TiO2 was used as photocatalyst, Rh-110 was produced only under visible light irradiation. Instead, RhB would be oxidized completely under ultraviolet irradiation or using the annealing Ag/TiO2. Although there were many photocatalysis degradation mechanisms of RhB in previous literatures, we have not found an appropriate mechanism to explain this phenomenon. Radical-trapping tests indicated that the effect of superoxide anion radical was more important than hydroxyl radical in the forming process of Rh-110, and hence the selective oxidation mechanism of Ag/TiO2 was suggested according to the role changing of Ag nanoparticles on the composites under visible and ultraviolet irradiation.