Preparation and characterization of Ag-doped crystalline titania for photocatalysis applications

Five pure and silver-enriched TiO2 catalysts with various Ag loading (0-5.2 wt.%) were prepared by the sol-gel technique from nonionic surfactant Triton X-114, cyclohexane, water (or water solution of AgNO3) and metal precursor. Calcination at 400 degrees C for 4 h was applied to convert prepared gels to pure anatase crystalline powders. Effects of silver doping on titanium photocatalyst properties were evaluated by nitrogen physical adsorption. X-ray diffraction, elemental analysis, transmission electron microscopy, Raman spectroscopy, TGA analysis and UV-vis spectroscopy. Two green photocatalytic reactions were chosen for photocatalytic experiments: photocatalytic reduction of CO2 and photocatalytic oxidation of 4-chlorophenol (4-CP) water solution. Both photocatalytic reactions were carried at mild conditions (room temperature and ambient pressure or pH 7). The activity of titania catalysts for photocatalytic reduction of CO2 was evaluated individually with respect to various UV lamps (254 and 365 nm). The UV lamp with wavelength in the range 250-420 with highest maxima at 254 and 365 nm was used for photocatalytic oxidation of 4-CP. The dependence of the photocatalytic activity on increase of Ag content was evaluated for both reactions and compared with the photocatalytic activity of Degussa catalyst P25. (C) 2011 Elsevier B.V. All rights reserved.