Photocatalytic properties of surface modified platinised TiO2: Effects of particle size and structural composition

Some parameters that may have an influence on the photocatalytic activity of TiO2 modified by platinisation have been studied, including structural composition, source of TiO2 or platinum-deposit size. A wide number of different TiO2 was used for the study: commercial TiO2 Degussa P25, Hombikat UV-100 and Rutile Aldrich as well as TiO2 prepared by sol–gel method in our laboratory. Platinisation was performed in all cases over the different TiO2 by photodeposition of platinum from hexachloroplatinic(IV) acid (H2PtCl6), depositing an amount of 0.5% Pt (weight total to TiO2) and using isopropanol as reducting agent under N2 atmosphere. All samples were widely characterised: surface area and porosity, phase composition and crystallite size, UV–vis absorption properties, etc. The study of the platinum deposit sizes was attempted by transmission electron microscopy (TEM). The enhancing or detrimental effect of the platinum deposits on the photocatalytic activity of the different TiO2 for phenol oxidation was studied in correlation with the results of structural and surface characterisation.