Effect of Pt/TiO2 characteristics on temporal behavior of o-cresol decomposition by visible light-induced photocatalysis

Platinum deposited TiO2 films were prepared on quartz substrates by dip-coating process for the photodecomposition of o-cresol. The characteristics of Pt/TiO2 and the temporal behavior of o-cresol decomposition by Pt/TiO2 photocatalysis under visible light irradiation were investigated. Platinum deposited on TiO2 photocatalysts was characterized by Brunauer–Emmett–Teller (BET) surface area measurement, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), diffuse reflectance UV–Vis spectra (DRS) and photoluminescence (PL) emission spectra. The results indicated that the deposition of platinum on TiO2 promoted the optical absorption in the visible region and made it possible to be excited by visible light. The decomposition rate of o-cresol under visible light irradiation from a fluorescent lamp was enhanced to noticeably extents for experiments conducted with Pt/TiO2 containing platinum up to 0.50 wt% platinum because of the presence of Ti3+ resulted from the platinum deposited on the TiO2 surface; and the formation of Schottky Barrier between platinum and TiO2 preventing the recombination of electric holes and electrons. Specifically, the reaction rate of o-cresol photodegradation at pH 9 using the 0.50 wt% Pt/TiO2 was 4.8 times than that of using pure TiO2. The intermediates identified by GC/MS spectroscopy during the photocatalytic oxidation of o-cresol. The proposed kinetic model could be adequately applied to describe the temporal behavior of the o-cresol decomposition with and without the dosage of Pt on TiO2 in aqueous solution by UV/TiO2 process.