Effect of the photoinduced hydroxyl radicals of TiO_2 nanoparticles on the photocatalytic performance

By means of X-ray diffraction (XRD) and photo-degradation of Rhodamine-B (RhB), the crystalline structure and photocatalytic activity of the TiO_2 prepared by sol-gel method were studied, and the active oxidative species (·OH) produced in the supernatant liquid of the irradiated TiO_2 suspension containing terephthalic acid were also investigated by measuring the fluorescence derived by the reaction with terephthalic acid. It was found that the formation rate of ·OH and the photocatalytic efficiency were greatly influenced by the crystalline structure of TiO_2. The results also indicated that the greater the formation rate of ·OH was, the higher photocatalytic activity of TiO_2 was achieved.