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 TiO 2 nanocrystals 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 TiO 2 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 TiO 2 nanocrystals were examined in the degradation of RhB under artificial solar light. We found that the TiO 2 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 TiO 2 P25. The possible mechanism of brookite/rutile ratio tuning was proposed on the basis of characterization.