An Approach for Controllable Synthesis of Different-Phase Titanium Dioxide Nanocomposites with Peroxotitanium Complex as Precursor

In this paper, we describe a systemic approach for the preparation of different-phase titanium dioxide nanocomposites with peroxotitanium complex (PTC) as a precursor in aqueous solution by a low-temperature process. Three phases (anatase, rutile, and brookite) of TiO2 nanoparticles were prepared by refluxing the PTC precursor at different pH values at 100 degrees C and ambient pressure. At pH = 0, acicular rutile-phase nanoparticles were prepared, while at a pH of about 1, a stable milk white sol that contains about 63% brookite phase was obtained; the brookite particles are mainly irregular quadrate. Furthermore, the spherical and spindle anatase nanoparticles were prepared from the precursor with pH = 3 and 6, respectively. The influence of the different concentration of the peroxide on the products was also investigated. It is noticed that there was an optimum H2O2/Ti molar ratio for different phase formation. Finally, the photocatalytic properties of different products were measured by decomposing methylene blue. The spherical anatase phase showed higher photocatalytic degradation rates for methylene blue than others.