A new photocatalyst: Bi2TiO4F2 nanoflakes synthesized by a hydrothermal method

Abstract

A pure phase of Bi₂TiO₄F₂ 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 Bi₂TiO₄F₂ are explored by degradation of Rhodamine B (RhB) and phenol. The results show that Bi₂TiO₄F₂ exhibits much higher photocatalytic performances than Bi₄Ti₃O₁₂ 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 Bi₄TiO₄F₂ in solution, in agreement with the proposed mechanism. Thus, Bi₂TiO₄F₂ can be used as a new efficient photocatalyst.