Silver and Indium Oxide Codoped TiO₂Nanocomposites with Enhanced Photocatalytic Activity

Abstract

Metallic silver and semiconductor indium oxide codoped titania nanocomposites were prepared by a one-step sol−gel-solvothermal method in the presence of a triblock copolymer surfactant (P123). The resulting Ag/In 2O 3−TiO 2 three-component systems mainly exhibited an anatase phase structure, high crystallinity, and extremely small particle sizes with metallic Ag particles well-distributed on the surface. Compared with pure anatase TiO 2, the Ag/In 2O 3−TiO 2 systems showed narrowing of the band gap due to the change in the band position caused by the contribution of the In 5s5p orbits to the conduction band. By tuning loadings of Ag or In 2O 3 and molar ratios of titanium source to the surfactant, size and dispersion of the product particles can be controlled. As-prepared Ag/In 2O 3−TiO 2 nanocomposites were used as the photocatalysts to degrade dye rhodamine B (RB) and methyl ter-butyl ether (MTBE) in the liquid phase. At 2.0% Ag and 1.9% In 2O 3 doping, the Ag/In 2O 3−TiO 2 system exhibited the highest UV-light photocatalytic activity, and nearly total degradation of dye RB (25 mg L −1) or MTBT (200 mg L −1) was obtained after 45 or 120 min UV-light irradiation. In addition, the UV-light photocatalytic activity of three-component systems exceeded that of the single (TiO 2) and two-component (Ag/TiO 2 or In 2O 3−TiO 2) systems as well as the commercial photocatalyst, Degussa P25. Reasons for this enhanced photocatalytic activity were revealed.