Doped TiO2: the effect of doping elements on photocatalytic activity

Abstract

Doping of TiO₂ with various elements increases its photocatalytic activity due to the formation of new energy levels near the conduction band. Photocatalysis involving titanium dioxide is a heterogeneous process in which the surface of the catalyst plays an important role. The structural properties of TiO₂ are influenced by the synthesis method, the doping method, and the dopants. In this work, we compare different doping elements for improving the photocatalytic activity of titanium dioxide, which was synthesized by the sol–gel method. In the doping method, low-temperature underwater plasma was used. Al, Cu, Mo, and W acting as electrodes were chosen as doping elements. The obtained samples were characterized by various techniques. The incorporation of elements leads to the distortion of the TiO₂ crystal lattice, thus changing its surface characteristics, and to a decrease in the band gap. The introduction of aluminum and copper increases the photocatalytic activity to 70% while doping with Mo and W increases the activity to 96% upon visible light irradiation for 60 minutes. Explanations of the effect of various doping elements on the photocatalytic activity of titanium dioxide are presented.