Preparation And Photocatalytic Properties Of TiO2-based Nanomaterials

In recent years, semiconductor catalysts have received increasing attention because of their commendable properties in air-cleaning, water purification, antibiosis, sterilization, antifogging, antifouling and self-cleaning. TiO2is one of the most studied materials thanks to its chemical stability, nontoxic and efficient photosensitivity among a large number of semiconductor photocatalysts, while the photocatalytic efficiency of TiO2is limited by its poor absorption with organic pollutants, low quantum efficiency, and low utilization of visible light. Here we focus on improving the photocatalytic efficiency of TiO2through different methods, which includes increaseing specific surface areas and coupling with ZnO and V2O5, and the photocatalytic mechanism is studied systematically. This provides experimental basis and theoretical basis for the further application of the TiO2-based nanomaterials. The main results of the present work are as follows:1. TiO2nanowires are prepared by electrospinning method, ZnO nanoparticles are prepared by coprecipitation, and V2O5nanospheres are prepared by chemical vapour deposition at a relatively low temperature using VO(acac)2powder as the vanadium precursor. Then, the photocatalytic properties of TiO2nanowires, ZnO nanoparticles and V2O5nanospheres are studied, the results show that the photocatalytic ability of TiO2nanowires is the highest under a commercial lamp, the photocatalytic efficiency of ZnO nanoparticles is not as good as the TiO2nanowires, and the V2O5nanospheres show almost no photocatalytic ability. This indicates that the TiO2nanowires with high photocatalytic activity are prepared. At the same time, electrospinning has provided a simple approach to fabricate exceptionally uniform nanofibers, and it is a much promising photocatalysts preparing method.2. TiO2/ZnO nanomaterials with high photocatalytic efficiency are prepared by electrospinning. The TiO2/ZnO nanomaterials are successfully prepared by electrospinning the PVP/zinc nitrate/TiO2nanofibers solution. The influence of the solvent system to the morphology of the TiO2/ZnO nanomaterials is studied, it is found that the diameter of TiO2/ZnO nanofibers prepared at water solvent system is about100nm, and the diameter of TiO2/ZnO nanofibers prepared at alcohol solvent system is about500nm. Finally, the photocatalytic properties of TiO2/ZnO nanomaterials are studied, the photocatalytic efficiency of TiO2/ZnO nanomaterials is much higher than that of pure TiO2nanofibers. This is because that the photogenerated electrons and holes are highly separated. Furthermore, the photocatalytic activity of TiO2/ZnO nanocomposites materials with smaller diameter is higher, which is due to the large specific surface areas.3. TiO2/V2O5nanoheterostructures are prepared by electrospinning and sputtering. The influence of sputtering power to the formation of the TiO2/V2O5nanoheterostructures is studied, and150W is the best condition for the sputtering. The photocatalytic efficiency of the TiO2/V2O5nanoheterostructures is about5times faster than that of pure TiO2nanofibers, revealing that the visible light induced catalytic activity of the TiO2/V2O5nanoheterostructures is greatly improved. The enhancement of the photocatalytic activity of the TiO2/V2O5nanoheterostructures can be ascribed to the coupling with a small bandgap semiconductor material V2O5, where the absorption range is extended and the photogenerated electrons and holes are highly separated. Additionally, TiO2/V2O5nanoheterostructures show excellent photocatalytic stability after10cycles. This indicates that the coupling of V2O5and TiO2is an effective way to improve the photocatalytic efficiency of TiO2, and it provides a new way for us to quest for highly efficient photocatalysts.4. The preparation method of the TiO2/V2O5nanoheterostructures is improved, and the TiO2/V2O5nanoheterostructures with high photocatalytic activity are synthesized via electrospinning directly. The photocatalytic efficiency of the TiO2/V2O5nanoheterostructures is about8times higher than that of pure TiO2nanofibers, it shows excellent photocatalytic stability, and the photodecomposition rate of RhB still keeps at about95%after10cycles using TiO2/V2O5nanoheterostructures as photocatalysts. Furthermore, the influence of V/Ti molar rate and annealing temperature on the photocatalysis is also studied. Experimental results indicate that appropriate amount of V2O5can improve photocatalytic activity and the photocatalytic activity decreases with the increase of annealing temperature. In addition, the TiO2/V2O5nanoheterostructures have the highest photocatlytic efficiency when the V/Ti molar ratio is1:1. The one-step preparation of TiO2/V2O5nanoheterostructures by electrospinning provides a possibility for the mass production of the highly efficient photocatalysts.