Controllable One-Pot Synthesis and Enhanced Photocatalytic Activity of Mixed-Phase TiO2 Nanocrystals with Tunable Brookite/Rutile Ratios

We report a one-pot facile hydrothermal method to synthesize mixed-phase TiO2 tranocrystals with tunable brookite-to-rutile ratios. This method utilizes titanium tetrachloride as the titanium source and triethylamine as the adjusting reagent to tune the ratio of brookite and rutile in mixed-phase TiO2 nanocrystals. The resulting samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), UV-vis diffuse reflectance spectroscopy (UV-vis), and nitrogen sorption measurements. The photocatalytic activities of the resulting TiO2 nanocrystals were examined in the degradation of RhB under artificial solar light. We found that the TiO2 sample with 38% brookite and 62% rutile, obtained in a solution of 3 mL of triethylamine and 10 mL of water, exhibited the highest photocatalytic activity. Its activity was about 6 times of that of the Degussa TiO2 P25. The possible mechanism of brookite/rutile ratio tuning was proposed on the basis of characterization.