Solution Synthesis And Photocatalytic Properties Of Aurivillius Bi₂TiO₄F₂ And Its Composites

In the past decades, environmental pollution and energy crisis have been two main issues of concern. Due to the application on photocatalytic water-splitting hydrogen production and degradation of organic pollutants, semiconductor photocatalysis technology has become one of the most promising solutions for environmental pollution and energy crisis. Aurivillius bismuth-based semiconductor photocatalytic materials have unique layered structure,which can promote the separation and transfer of photogenerated electron-hole pairs between [Bi₂O₂]²⁺ layers and perovskite layer, and thus the enhancement of photocatalytic performance. Bi₂TiO₄F₂, one of the Aurivillius semiconductors, has attracted little attention as photocatalytic material. In this thesis, Bi₂TiO₄F₂ and its composites were successfully prepared via a solvothermal route, and the photocatalytic properties of the products were also systematically studied. The main research results are as follows:?1? Bi₂TiO₄F₂ hollow microspheres were synthesized via a solvothermal route under 150°C using TiO₂ and Bi?NO3?3 as the raw materials. The photocatalysts were characterized by X-ray powder diffraction?XRD?, field emission scanning electron microscopy?FESEM?, transmission electron microscopy?TEM?, N₂ adsorption–desorption, and UV-vis diffuse reflectance spectroscopy?DRS?. Based on the evolution of phases and morphologies, a possible growth mechanism of Bi₂TiO₄F₂ hollow microsphere was also proposed. Bi₂TiO₄F₂ showed high catalytic activity in degradation of RhB and MO under UV-light. When under the irradiation of visibile light, the degradation efficiency of MO was relatively low. As for the visibile light degradation of RhB, it should be based on the photosensitization.?2? BiF₃-Bi₂TiO₄F₂ composite was synthesized via a solvothermal route under 150°C using TiO₂ and excess Bi?NO3?3 as the starting materials. The photocatalyst was characterized by X-ray powder diffraction?XRD?, field emission scanning electron microscopy?FESEM?, and UV-vis diffuse reflectance spectroscopy?DRS?. The UV-Vis test showed that the band gap of BiF₃-Bi₂TiO₄F₂ was obviously narrowed compared with Bi₂TiO₄F₂. The degradation results indicated that BiF₃-Bi₂TiO₄F₂ composite exhibited higher photocatalytic activity for both RhB and MO under UV-light. In the condition of visibile light irradiation, BiF₃-Bi₂TiO₄F₂ composite still exhibited high photocatalytic activity for MO and higher photocatalytic activity for RhB compared with pure Bi₂TiO₄F₂.?3? Based on the synthesis of Bi₂TiO₄F₂ pure phase, Ag nanoparticles were further deposited on the surface of Bi₂TiO₄F₂ hollow microspheres via the two-step method. The obtained photocatalyst was characterized by X-ray powder diffraction?XRD?, field emission scanning electron microscopy?FESEM?, Energy Dispersive Spectrometer?EDS?, and UV-vis diffuse reflectance spectroscopy?DRS?. The dye degradation results showed that the as-prepared Ag-Bi₂TiO₄F₂ composites exhibited higher photocatalytic activity for both RhB and MO under visible light compared with pure Bi₂TiO₄F₂.