Influence of solvent type on the characteristics and photocatalytic activity of TiO 2 nanoparticles prepared by the sol–gel method

TiO2 nanoparticles were prepared by the sol–gel method using methanol, ethanol and isopropanol as solvents and titanium tetraisopropoxide as a precursor. The prepared TiO2 nanoparticles were characterised by X-ray diffraction, scanning electron microscopy, nitrogen physisorption and UV-vis diffuse reflectance spectroscopy. The results indicated that the TiO2 nanoparticles prepared in isopropanol displayed pure anatase crystalline phase with the smallest crystallites having an average size of 11.4 nm. However, the TiO2 nanoparticles prepared in methanol and ethanol contained anatase- and rutile-mixed phases with anatase crystallite sizes of 15.6 and 14.5 nm, respectively. Nitrogen physisorption results showed that, compared to the TiO2 nanoparticles prepared with isopropanol, TiO2 nanoparticles prepared with ethanol had a greater pore volume and pore size, which led to their higher photocatalytic activity. The photocatalytic activities of the prepared TiO2 nanoparticles in the photodegradation of C.I. Basic Violet 2 (BV2) were compared to the activity of Degussa P25 TiO2. The maximum photodegradation rate of BV2, obtained from the TiO2 nanoparticles prepared in ethanol, was 3.5, 1.7 and 1.4 times greater than that of TiO2 particles prepared in isopropanol and methanol and the commercial Degussa P25 TiO2, respectively.