| The oxide film of TiO2nanotubes prepared by anodic titanium which have a special topography structure and large surface area, exhibited a vast application in the field of photocurrent response, photocatalytic activity, dye-sensitized solar cells, electrochemical devices and gas sensors. Generally, TiO2nanotubes are obtained by anodization Ti foil in which prepared TiO2nanotubes always present a layer of residual titanium underneath the nanotubes. This residual titanium has highly conductivity which results in an electrical short-circuit for devices and Ti-foil based nanotubes are opaque limits the application in optics devices. The main research of this paper include:using a method of anodic Ti film to prepare TiO2nanotube; the effect of anodizing parameters on the morphology change of TiO2nanotube; the effects of annealing temperature on the crystal structure of TiO2nanotubes, and the performance of TiO2nanotube to photocatalytic degradation of Methylene Blue. The specific process as follow:The Ti films deposited by Middle frequency pulse magnetron sputtering on the ordinary glass substrate, different structure of the Ti films prepared by by changing the sputtering pressure, substrate temperature and substrate bias. The results show that:the Ti films with dense structure and good adhesion were obtained by sputtering power of350W, sputtering pressure of0.2Pa, and substrate temperature of300℃The Ti films with different type of structure were anodized in the electrolyte of0.75wt%NH4F+glycol+3vol%H2O. It is found that Ti films with dense structure benefit for the formation of TiO2nanotubes. From the formation mechanism of TiO2nanotubes to point that anodizing Ti films with dense structure was benefit the formation of TiO2nanotubes because that in anodization process could not lead to the Electronic gathering.TiO2nanotubes with different length were obtained by anodize different thickness of the Ti films. The result shows that:the length of TiO2nanotube was1.5-2times than the thickness of titanium film after anodized. TiO2nanotubes with different diameter were obtained by changing the anodization voltage. And it is also found that the linear relationship between the diameter of TiO2nanotube and anodization voltage. The diameter of the TiO2nanotubes ranging of55nm to135nm was under the anodization voltage of30V-60V. The effection of the composition of the electrolyte (fluoride ion concentration, Water content, etc.) to morphology structure of the TiO2nanotube was studied. The results show that the TiO2nanotube with great orderly array and good morphology structure could obtain in electrolyte of lwt%NH4F+ethylene glycol+6vol%H2O. When the concentration of the NH4F below0.75wt%, the layer of formed TiO2only show nanopore morphology, even under the high anodic oxidation voltage.In the anodization process, increasing the thickness of the titanium film at the interface, could prepare the transparent TiO2nanotube coating glass, which the diameter of the nanotube was100nm, the length of the nanotube was800nm and the transmission could achieve to89%. The heat treatment process could achieve the crystal transformation of TiO2nanotubes. When the temperature was250℃, transformation from amorphous phase to anatase phase was apperenced. When the temperature came to680℃, rutile phase transition was apperenced.The performance of TiO2nanotube was measured by photocatalytic degradation of Methylene Blue. The results showed that:TiO2nanotubes degrade methylene blue under photocatalytic fit the reaction equation of first-order kinetics. A higher efficiency of photocatalytic degradation of methylene blue was obtained under the450℃. The diameter of TiO2and the tube length have a major influence on photocatalytic performance. And it is found that TiO2nanotubes with diameter of105nm and length of2.8μm could achieve the high rate of photocatalytic degradation for methylene blue, within two hour the degradation rate achieved to90%. |
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