Promoted phase transition of titania nanoparticles prepared by a photo-assisted sol-gel method

A simple and efficient methodology, in which ultraviolet irradiation was introduced into the preparation of the titania colloids, has been established for the synthesis of phase-pure anatase with a grain size of about 3.6 nm at calcination temperatures as low as 100 °C. The XRD and Raman results indicate that the phase transition of TiO2 from amorphous to anatase is promoted by UV light irradiation. It is also documented that the promoted formation of anatase upon calcination is due to the oxygen vacancy defects induced by photo-irradiation of the colloid during the sol-gel process.