Nanocrystalline anatase TiO2 photocatalysts prepared via a facile low temperature nonhydrolytic sol–gel reaction of TiCl4 and benzyl alcohol

Abstract

Nanocrystalline anatase TiO2 photocatalysts prepared by a facile nonhydrolytic sol–gel (NSG) reaction of TiCl4 and benzyl alcohol at low temperature, followed by subsequent calcination at elevated temperatures were investigated in relation to their performance in the photocatalytic degradation of phenol. A variety of techniques including N2 adsorption, X-ray powder diffraction (XRD), diffuse reflectance FTIR spectroscopy (DRIFTS), thermogravimetric measurements (TG/DTA), transmission electron micrographs (TEM), and X-ray photoelectron spectroscopy (XPS) were employed to characterize the resulting materials. It is shown that the fresh nanocrystalline TiO2 sample obtained by the low temperature NSG process exhibits considerable activity comparable to that of commercial photocatalyst Degussa P-25, although evidence shows it to be surface-capped with appreciable amount of organic moieties. Moreover, it is demonstrated that the catalytic efficiency of the as-prepared nanocrystalline TiO2 sample can be further markedly enhanced by subsequent thermal treatment at elevated temperatures ranging from 300 to 600°C. Both the calcination temperature and calcination time appear to be crucial factors in influencing a number of critical properties of the calcined TiO2 samples such as the surface area, particle size, crystallinity, amount of surface hydroxyl groups, as well as carbonaceous residues. The TiO2 photocatalyst obtained by calcination at 400°C for 3h exhibits the highest activity toward photocatalytic degradation of phenol.