Synthesis of TiO2 sol in a neutral solution using TiCl4 as a precursor and H2O2 as an oxidizing agent

Abstract Nanosize TiO 2 thin film on glass substrate was obtained through dip-coating method using TiO 2 sol. Suspended nanosize TiO 2 sols with anatase structure in aqueous solution were synthesized by sol–gel method using TiCl 4 as a precursor. TiCl 4 was reacted with an aqueous solution of NH 4 OH to form Ti(OH) 4 , and H 2 O 2 was then added to form peroxo titanic acid. It was further heated in water and converted to TiO 2 . The effects of the preparation parameters, viz., pH value of the Ti(OH) 4 gel, concentration of H 2 O 2 , and heating temperature and time, on the properties of the TiO 2 sol were investigated. The materials were characterized by X-ray diffraction, Fourier transform-infrared spectroscopy, and transmission electron microscopy. The results showed that the primary TiO 2 particles were rhombus with the major axis ca. 10 nm and minor axis ca. 4 nm, and were in anatase structure. The sol was excellent in dispersibility and was stable in neutral and even slight basic conditions for at least 2 years without causing agglomeration. The best preparation condition was optimized with the pH value of Ti(OH) 4 gel at 8, H 2 O 2 /TiO 2 mole ratio of 2, and heating at 97 °C for 8 h. The transparent adherent TiO 2 film on glass substrates exhibits strong hydrophilicity after illuminating with ultraviolet light and it can be used as an efficient photocatalyst.