Photocatalytic Removal of Phenol Under UV Irradiation on WOx–TiO2 Prepared by Sol–Gel Method

New WOx–TiO2 photocatalysts were prepared via sol–gel method from tetraisopropyl orthotitanate and WO2. For comparison TiO2 was also prepared by the same method. These photocatalysts were tested for phenol degradation in an aqueous solution under UV irradiation. Experimentally measured OH radicals formation on WOx–TiO2 photocatalysts was quantitatively much higher than on TiO2, what increased their photocatalytic activity towards phenol decomposition. Band gap of the prepared photocatalysts was calculated from the obtained derivatives of UV–Vis/DR spectra and it was observed that Eg decreased with increasing calcination temperature in both, TiO2 and WOx–TiO2. This was caused by the improving crystallinity of anatase phase and formation of rutile, which had a lower value of Eg than anatase. In general the presence of WOx in TiO2 suppressed transformation of anatase to rutile.