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

Abstract

This paper deals with the oxidation of benzyl alcohol by O₂ 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 α-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.