Synthesis, characterization and photocatalytic activity of different metal-doped titania systems

Different titania-based systems doped with diverse transition metals (Ag, Fe, Pd, Pt, Zn and Zr) were synthesized by the sol–gel method. Samples were characterized by a wide range of physical techniques (ICP-MS, N2-isotherms, TGA–DTA, TEM, XRD, FT-Raman and UV–vis spectroscopies). The effect of aging of the gel either under magnetic stirring (ST) or ultrasonic irradiation (US) on the characteristics of the resulting solids was studied. Sonication ensured the obtention of pure anatase nanoparticles and generally led to an increase in surface area. All the solids were tested for gas phase selective photooxidation of 2-propanol. Irrespective of the aging method, doping with Pd, Pt or Ag resulted in an increase in molar conversion as compared to bare-TiO2, whereas the presence of Fe and Zr had a detrimental effect. Those solids for which sonication had the greatest impact on textural and structural characteristics (bare-TiO2 and Zn-containing samples) exhibited the greatest difference in molar conversion. Moreover, high selectivities to acetone were achieved in most of the cases.