The Preparation And Photocatalytic Properties Of TiO₂ Nanotubes Research

TiO2 is a kind of environmental friendly, non-toxic and stable chemical properties inorganic functional materials, in the recent 20 years,TiO2 rapid development in the field of photocatalysis and photodegradation. In biomedical coating, photovoltaic devices, sensors, air purifiers, water processor has a great application prospect. With the deepening of the research, the scientists found that nano TiO2 than nanoparticles have better physical and chemical properties. Because the TiO2 nanotubes has larger specific surface area.It is expected to improve the photoelectric conversion efficiency and light catalytic performance of TiO2.In this paper, Based on ethylene glycol-ammonium fluoride electrolysis system, successfully in pure titanium surface prepared TiO2 nanotubes array aperture. Used rutile type nanometer titanium dioxide as precursors with strong alkali in ptfe lining for thermal water kettle thermal water, succeeded making TiO2 nanotubes. Using X-ray diffraction(XRD), scanning electron microscope (SEM), uv-visspectrophoto-meter(UV-VIS) method describe the preparation of nanometer TiO2 materials’s crystal structure, surface morphology and Photocatalytic activity. The main results were as follows:Scanning electron microscopy (SEM) analysis known that the oxidation voltage and the concentration of ammonium fluoride is crucial influence on the morphology of pipe, the reaction time only affects the length. The best preparation conditions for the oxidation voltage 60V, the reaction time of 12h, the quality of the ammonium fluoride concentration is 0.25wt%. Hydrothermal preparation of nanometer TiO2 tube morphology related to reaction temperature and concentration of alkali. The best alkali concentration for 10mol/L, the reaction temperature of 160 ℃.X-ray diffraction (XRD) analysis shows that.Anode anode oxidation preparation of nanometer TiO2 tube in the heat treatment temperature of 350 ℃, the amorphous TiO2 into the start of the sample anatase TiO2.When the heat treatment temperature reaches 450 ℃, the diffraction peak of TiO2 rutile type began. The heat treatment temperature reaches 650 ℃, TiO2 anatase type completely turned the rutile type of TiO2. TiO2 nanotubes has good thermal stability, temperature below 650 ℃ almost won’t destroy the morphology of the nanotubes. Hydrothermal preparation of nanometer TiO2 tube through 400 ℃,500 ℃,600 ℃ nanotube crystal structure has not changed after heat treatment, always is the anatase type.BET experiment can confirm that hydrothermal method in the preparation of nanometer TiO2 tube under the conditions of different alkali concentration of specific surface area is much bigger than precursors. In alkali concentration for 10mol/L, the specific surface area of the sample is reached more than six times the precursors of 310.25 m3/g.Used the nanometer TiO2 as catalyst photocatalytic degradation of methylene blue solution to get the following conclusion:Under the condition of different voltage and concentration of ammonium fluoride preparation of TiO2 nanotubes because of its difference, surface morphology and structure has important influence on its photocatalytic performance. With the increase of voltage, preparation of nanotubes for the degradation of methylene blue rate rising. Oxidation voltage 60 v, ammonium fluoride catalytic effect when the mass concentration of 0.25% for the best.Heat treatment temperature on the hydrothermal preparation of nanometer TiO2 photocatalytic performance impact is not big, because of its crystal shape does not change along with the heat treatment temperature. For anodic oxidation is significantly influenced the preparation of nanometer TiO2 tube.The concentration of methylene blue on the hydrothermal method and anodic oxidation method are of great effects on the photocatalytic properties of the TiO2 nanotubes. With the increase of the concentration of the methylene blue adsorption process on the surface of the catalyst gradually replace the formation process of hole-electron pair as the control process of degradation of methylene blue.Due to the adsorption capacity on the surface of the catalyst is limited, with the increase of concentration, adsorption quantity increases more and more difficult, cause the degradation rate of decline. Second, methylene blue is a stain, with the increase of concentration, the color of the solution will be deepened, it will block the light reaches the catalyst surface and the photolysis of methylene blue.