Fabrication And Photocatalytic Applications Of TiO₂ Nanotube Arrays-Based Nanomaterials

In recent years, with China's rapid economic development, energy shortages,environmental pollution and the people's lives, physical health become increasingly serious problems. In this thesis, considering photocatalytic sterilization of titanium dioxide as goal, to improve the optical/electrical activity of the titanium dioxide nanotube arrays, we carry out fundamental research in titanium dioxide nano-composite materials, and their applications in the field of organic pollutants removing and biological bactericidal killing.Since 2001, TiO₂ NTs prepared by anodization for the first time aroused great interest. So far, there have been a number of studies demonstrate TiO₂ nanotube arrays?TiO₂ NTs? have been found great application prospects in photocatalytic and biological fields, due to their highly ordered orientation, uniform surface morphology,adjustable pore size, length and special electrical, optical properties. However, the wide band gap of TiO₂?rutile Eg=3.0 e V, anatase Eg=3.2 eV? limits its effective utilization of sunlight since it can only absorbs 5% UV light?<390 nm?. On the other hand, the low conductivity of TiO₂ semiconductor materials can not effectively transfer the photogenerated pairs. The high photogenerated electrons-holes recombination reduces the photoconversion efficiency. This thesis studies the issues above, through doping and modification of the TiO₂ NTs, we enhance their absorption in visible light, increase the photoconversion efficiency and application the composites materials in the removaling of the organic pollution and biological sterilization field. The main research contents are as below:?1? Preparation and research on photoelectric properties of CuInSe₂/TiO₂NTs: TiO₂ NTs prepared by anodic oxidization of a pure titanium sheet in electrolyte solutions containing fluoride ions, with a lot of oxygen on the titanium surface. The titanium surface was first electrochemically oxidized to form a layer of dense oxide under which NTs were originated and slowly thicken. Reducing of titanium sheet also indicates that the F- chemical dissolution is very significant. CuInSe₂ nanocrystals were fabricated by a facile solution synthesis. Then the nanocrystals were deposited on to TiO₂ NTs by immersing the TiO₂ NTs in a CuInSe₂ nanocrystal ink, leading to high photoelectrical conversion efficiency in the visible region. CuInSe₂/TiO₂ NTs showed significantly enhanced photocatalytic activity towards 2,4-dichloro-phenoxyacetic acid?2,4-D? and anthracene-9-carboxylic acid?9-An COOH? under visible light. Photoelectrochemical detection shows that exhibits high efficiency of photocatalytic degradation.?2? Preparation and research on photoelectric bactericidal of Cd S/Zn Se/TiO₂NTs: Based on the band matching principle, we selected appropriate narrow-band semiconductor materials to composite with TiO₂. Therefore, the modification of narrow-band semiconductor materials can not only enhance the absorption of visible light but also promote the photo-carriers separation, thereby enhancing the optical properties of composite materials. Based on this, we studied the photocatalyic properties of narrow-band binary or ternary semiconductor heterostructures Cd S/Zn Se/TiO₂ NTs composite materials. Cd S nanoparticles and Zn Se modified TiO₂ NT arrays shows enhanced bactericidal effect to E. coli.