In order to maximize the reactivity of photocatalyst, the transmission rate of electrons, that were produced by absorbing light energy, need to be increased in order to suppress their recombination with holes. Titanium oxide nanotubes are called electron highway, because electrons can move freely through the nanotubes. For that, titanium oxide nanotubes were anodized by various conditions, and its reaction rate was compared to photocatalytic reaction and potential applied photoelectrocatalytic reaction, and they were characterized by XRD, FE-SEM and UV-DRS.
The electrolytes used in anodization for preparing titanium oxide nanotubes were HF+acetic acid, KF+NaHSO4 and NH4F+glycerol, and for the anatase crystal growth of the prepared titanium oxide nanotubes, calcination was carried out. The diameter of the titanium oxide nanotubes prepared by anodizing was 50nm to 150nm, and their length was 300nm to several micrometers. In the XRD analysis of titanium oxide nanotubes after calcination, anatase crystals, which have photocatalytic activity, appeared. In the photocatalytic degradation of dye using titanium oxide nanotubes, the degradation rate was the twice in comparison to that using conventional titanium oxide thin films that was prepared by sol-gel and anodizing. It is interpreted that titanium oxide nanotubes quickly transmit the electrons to inside, and suppress their recombination with the holes, thus increase the production of OH radicals that are used in photocatalytic reactions. When electric potential was applied to titanium oxide nanotubes, the degradation rate was increased by about 50%, but the effect of the length of titanium oxide nanotubes on reactivity was not big.