Water-assisted synthesis of anatase TiO2 nanocrystals:: Mechanism and sensing properties to oxygen at room temperature

High-crystallinity anatase TiO2 nanocrystals with the size of similar to 2-4 nm have been prepared by a facile and quick method at low temperature. Ethylene glycol was used to both control the hydrolysis and condensation rates of titanium isopropoxide. H2O used in this reaction system, is the key reagent for the anatase formation, and the amount of H2O has been demonstrated to be an important parameter for the fast anatase phase formation. The plausible reaction mechanism has been discussed on the basis of the results of SEM, TEM, HRTEM, XRD, UV-vis, FT-IR, and TGA measurements. By studying the sensing properties of the as-synthesized anatase nanocrystals, it has been found that the nanocrystals exhibit the fast response to oxygen under the UV illumination at room temperature.