Singlet oxygen photogeneration and 2,4,6-TCP photodegradation at Pt/TiO2 under visible light illumination

Pure and Pt nanoparticle-modified rutile TiO2 were synthesized via hydrolysis of TiCl4 in the absence or presence of Pt nanoparticles. HRTEM, XRD, and SEM were used to characterize the structure of the prepared catalysts. The resulting modified TiO2 catalysts show extended visible light absorbance. Photodegradation of 2,4,6-trichlorophenol (2,4,6-TCP) over these photocatalysts was investigated under visible light illumination. The Pt nanoparticles facilitate the separation of photogenerated electron-hole pairs at low Pt content, then enhances the photodegradation rate of 2,4,6-TCP. 0.18Pt-TiO2 achieved the best photocatalytic activity among the tested catalysts. It was found that singlet oxygen rather than (OH)-O-center dot acts as the main oxidative species for the degradation of 2,4,6-TCP according to the experimental results. The degradation intermediates of 2,4,6-TCP were identified and the degradation pathway was proposed. Pt nanoparticles on TiO2 significantly enhance O-2 adsorption and the formation of O-center dot(2). The rutile surface is a favorable condition for stabilizing O-center dot(2)-. These properties of the Pt nanoparticle-modified rutile TiO2 facilitate the formation of O-1(2) via the reaction of superoxide anions with holes.