Photocatalytic properties of nanocrystalline TiO2 modified with CuO and WO3

Abstract

Much attention is paid to studies of the processes occurring in heterogeneous catalysis with the use of nanomaterials, in particular, photocatalysis. Titanium dioxide and zinc oxide are among the most widespread photocatalysts due to their high chemical stability, suitable band gap, and rather high lifetime of nonequilibrium electron–hole pairs. In order to increase the photocatalytic activity (PCA) of these materials, including the case of a visible light action, various approaches are applied, in particular, the development of a composition material with a metal–semiconductor or semiconductor–semiconductor contact. We have chosen semiconductors of n-type (WO₃) and p-type (CuO) as components of such composites because of their potential positive influence on the PCA of titanium dioxide at the expense of spatial separation of nonequilibrium charge carriers and, respectively, increase in their lifetime. In order for the obtained composites to be commercially valuable, we have chosen a method of synthesis by modifying the ready TiO₂ preparations, including those that are commercially available (Degussa P25). It has been shown that the modification with CuO lowers PCA of titanium dioxide, while the modification with WO₃ enhances it by 25%. It has been demonstrated that WO₃/TiO₂ composite manifests PCA under visible light illumination.