Effect of Phase and Morphology of the TiO₂ Nanotube Array on Its Photocatalytic Activity

TiO₂ nanotube array（TNT） coatings were anodized on the titanium surface,and the effect of the phase and morphology of the TiO₂ on the photocatalytic activity was researched.The studies indicate that the photodegradation of organic contaminant by TNT depends on the hydroxyl radical which is synthesized by the photogenerated holes and oxidizer in the solutions,through depredating the contaminant by oxidizing the genes of organic compounds.By enlarging specific surface of aligned nanotube,the number of photoinduced electron in elemental area could increase,which results in improved degradation efficiency of organic contaminant.The less fluorine ion residues on the nanotube array,the higher percent of photodegradation.That’s because under UV irradiation,the negatively charged fluorine ion tends to react with positively charged photo-holes.In addition,due to the fluorine ion residues,Ti³⁺ appears in the nanotube,resulting in reduction of the electrons.Under conditions of low temperature annealing,the morphology of nanotube is not significantly altered.The main effect which can influence the property of semiconductor is phase conversion.Dominated with anatase structure,the TNT facilitates the separation and transmission of photogenerated electrons and holes,thus improving photocatalytic properties.