Hydrofluoric Acid Controlled TiO2 Phase Transformation from Rutile to Anatase at Room Temperature and Their Photocatalytic Performance.

In this study, we first present rutile TiO2 superstructures could be successfully transformed into anatase TiO2 nanoparticles at room temperature by adjusting the amount of hydrofluoric acid (HF) used in aqueous solution. Photocatalytic experiments demonstrated that the as prepared anatase TiO2 exhibited better photocatalytic performance than that of rutile TiO2. We further studied the photocatalytic degradation of RhB on different TiO2 via active species trapping experiments and confirmed that the presence of surface F- on TiO2 was beneficial for the formation of *OH, which was thought to be mainly responsible for the enhancement of photocatalytic performance.