Silver and indium oxide codoped TiO2 nanocomposites with enhanced photocatalytic activity

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/In2O3-TiO2 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 TiO2, the Ag/In2O3-TiO2 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 In2O3 and molar ratios of titanium source to the surfactant, size and dispersion of the product particles can be controlled. As-prepared Ag/In2O3-TiO2 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% In2O3 doping, the Ag/In2O3-TiO2 system exhibited the highest UV-Iight 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-Iight photocatalytic activity of three-component systems exceeded that of the single (TiO2) and two-component (Ag/TiO2 or In2O3-TiO2) systems as well as the commercial photocatalyst, Degussa P25. Reasons for this enhanced photocatalytic activity were revealed.