Characteristics of the charge transfer surface complex on titanium(IV) dioxide for the visible light induced chemo-selective oxidation of benzyl alcohol

This paper deals with the oxidation of benzyl alcohol by O-2 on pure TiO2 under visible light irradiation, and it was found that the benzyl alcohol is converted into benzaldehyde with high selectivity (>99%). In order to understand the origins of the visible light induced photocatalysis, surface characterizations of the charge transfer complex formed by the interaction of benzyl alcohol with the TiO2 was extensively performed by investigating the effect of heat-treatment on TiO2 or its chemical modification with hydrofluoric acid. Moreover, the study of the kinetic isotope effect (KIE) for the oxidation of benzyl alcohol showed that the alpha-deprotonation from benzyl alcohol is the rate determining step (RDS), the process of which is assisted by the terminal OH groups of TiO2. Photo-electrochemical investigations were also incorporated to demonstrate the reaction mechanism behind the visible light induced photocatalytic reaction.