An electron spin resonance spin trapping investigation of azide oxidation on TiO2 powder suspensions

Abstract

The oxidation of azide has been studied on TiO2 powder suspensions in water, methanol, and mixtures of the two solvents. The esr spin trapping technique has been employed to provide evidence for the formation of azidyl radicals [Formula: see text]. The results show that an aqueous alkaline medium is necessary to obtain a high production of [Formula: see text] radicals. A mechanism is proposed whereby the oxidation of [Formula: see text] is mainly due to reaction with OH• radicals which are in turn generated upon capture of holes by OH− groups adsorbed on TiO2. Azidyl anions adsorb weakly on TiO2 and do not displace adsorbed OH− from the surface.