Spectroscopic characterisation and photochemical behaviour of a titanium hydroxyperoxo compound

Abstract

In order to obtain more information about the generation of peroxide species during water photo-cleavage using M/TiO₂(M = noble metal) systems in which an O₂ evolution is normally not observed, a titanium hydroxyperoxo compound has been prepared by the reaction of TiCl₄ with H₂O₂. The structure and the thermal behaviour of this compound have been examined using TG-MS, XRD and TPD techniques. XPS, i.r., e.s.r. and u.v.-visible reflectance spectroscopy have been used to characterise the types of peroxo species present in this sample. The photochemical decomposition of this compound, which leads to O₂ evolution, has been studied compared to a TiO₂(Degussa P25) sample. A model is proposed to explain the lack of O₂ evolution during water photo-cleavage on M/TiO₂ systems where peroxo species, similar to those observed in the titanium hydroxyperoxo compound, become stabilised against photodecomposition.