Photoluminescence probing of the formation of titanium dioxide sols from a titanium peroxide solution

Photoluminescence spectroscopy was used to probe the formation of colloidal TiO2 sols from a titanium peroxide solution, which were prepared by reaction of H2O2 and titanium hydrate gel that was precipitated from acidic TiOCl2 solution neutralized by NH4OH, during aging at 100°C for 0-64 h. Emission spectra revealed broad band luminescence which is interpreted as the superposition of a multiple photoluminescence process involving TiO2 precursors. The maximum peak position of the luminescence band was shifted to a shorter wavelength by the generation of the dominant emission peak as aging time increased, and a peak at ∼390 nm, indicating the anatase phase, was observed after aging for >48 h. However, sols aged for 2 h already were of the anatase phase, according to X-ray diffraction analysis. It was deduced that the interfacial layers between the particles and the liquid in an aqueous solution caused luminescence quenching or accelerated sink.