Study On Preparation And Photocatalytic Properties Of Bi₄Ti₃O₁₂/O₂Heterostructure

TiO2has high catalytic activity, good chemical stability, non-toxic, low cost, widely used in the renewable energy and environmental protection field of applied research.However, due to its large band gap (about3.2eV for anatase), TiO2can only be activated under ultraviolet light no longer than387.5nm, which largely limits its overall efficiency under natural sunlight. In addition, the high rate of electron-hole recombination results in a low quantum yield and poor efficiency of photocatalytic reactions.In this paper, the Bi4Ti3O12/TiO2heterostructure was prepared via anodic oxidation and hydrothermal routes. Nano-array phase micro-structure, the photoelectric response characteristics and photocatalytic activity were studied, and we analyze the growth mechanism of the heterojunction. The main research results are as follows:1. Highly ordered TiO2nanotube arrays were synthetized by anodization in an ethylene glycol solution containing NH4F on high purity industrial Ti foil, and then annealed at450℃癈in air environment processing for1h. The crystal phases and the microstructure were observed with X-ray diffraction and scanning electron microscope, respectively. The optical property was investigated by UV-Vis.2. Using the hydrothermal reaction of TiO2nanotube arrays to prepare Bi4Ti3O12/TiO2heterostructure. Characterized the crystal structure and surface morphology of the heterostructure. And studied photoelectrochemical performance and photocatalytic properties of TiO2nanotube array and Bi4Ti3O12/TiO2heterostructure for different hydrothermal time. UV-visible diffuse reflectance spectroscopy demonstrated that TiO2nanotube arrays decorated with Bi4Ti3O12nanocube significantly enhanced the light absorption in the visible spectral range. And photoluminescence emission spectroscopy demonstrated that the heterostrucutre improved the separation of photo-induced charge carriers. After18h hydrothermal treatment, the sample showed the best photoelectrochemical properties, which is consistent with the results of the photocatalytic degradation.3. Analysis the formation mechanism of the heterosturcture by using nano-crystal nucleation and growth theory.photoelectrochemical performance-enhancing mechanism. The mechanism of the enhanced photoelectrochemical performance of heterostructure was discussed. The prominent photoelectrochemical performance could be ascribed to the heterostructure formed between Bi4Ti3O12and TiO2as well as a good dispersity of Bi4Ti3O12nanocubes, which could effectively separate the photogenerated carriers and reduce the electron-hole recombination and make the absorption band edge redshift.