A pure phase of Bi_2TiO_4F_2 nanoflakes with layered Aurivillius structure are synthesized by a simple hydrothermal method. The as-prepared sample is characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and UV-vis diffuse reflectance spectroscopy. The OH radicals produced during the photocatalytic reaction is detected by a photoluminescence (PL) technique. The electronic structure is investigated by DFT calculations. The photocatalytic properties of Bi_2TiO_4F_2 are explored by degradation of Rhodamine B (RhB) and phenol. The results show that Bi_2TiO _4F_2 exhibits much higher photocatalytic performances than Bi_4Ti_3O_(12) due to the unique layered structure and the existence of F. F acts as an electron trapper, which enhances the separation of photogenerated electron-hole pairs, and lead to higher photocatalytic activity. Reaction with terephthalic acid demonstrates that OH radicals are formed as a result of UV irradiation of Bi_4TiO _4F_2 in solution, in agreement with the proposed mechanism. Thus, Bi_2TiO_4F_2 can be used as a new efficient photocatalyst.
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