Deactivation and regeneration of ZnO and TiO2 nanoparticles in the gas phase photocatalytic oxidation of n-C7H16 or SO2

In this paper, we examined the lifetimes of made-in-home ZnO and TiO 2 nanoparticles in the gas phase photocatalytic oxidation of n -C 7 H 16 or SO 2 , and especially investigated the deactivation mechanism by utilizing surface photovoltage spectrum (SPS) and X-Ray photoelectron spectroscopy (XPS) testing techniques and by considering semiconductor chemical properties. The results showed that ZnO could almost be deactivated in the gas phase photocatalytic oxidation of n -C 7 H 16 , while TiO 2 could keep most of its activity. In the gas phase photocatalytic oxidation of n -C 7 H 16 or SO 2 , ZnO and TiO 2 both could almost be deactivated. The deactivation mainly resulted from semiconductor surface conduction type change from N-type before the photocatalytic reaction to P-type after the deactivation because of the adsorption of the oxidation products such as H 2 O, CO 2 and SO 3 on the semiconductor photocatalyst surface. In addition, the activity of the deactivated photocatalyst could be regenerated to a nearly full extent by washing and drying.