Photo-electrocatalytic activity of TiO2 nanotubes prepared with two-step anodization and treated under UV light irradiation

To improve the photo-catalytic degradation of salicylic acid, we reported the fabrication of ordered TiO2 nanotube arrays by a simple and effective two-step anodization method and then these TiO2 nanotubes were treated in a methanol solution under UV light irradiation. The TiO2 nanotubes prepared in the two-step anodization process showed better photo-catalytic activity than those prepared in one-step anodization process. Also, compared with TiO2 nanotubes without the UV pretreatment, the TiO2 nanotubes pretreated in a methanol solution under UV light irradiation exhibited significant enhancements in both photocurrent and activity. The treated TiO2 nanotubes exhibited a 5-fold enhancement in photocurrent and a 2.5-fold increase in the photo-catalytic degradation of salicylic acid. Also, the effect of addition of persulfate and periodate on the photo-catalytic degradation of salicylic acid was investigated. The results showed that the degradation efficiency of salicylic acid is increased with increasing persulfate and periodate concentrations. These treated TiO2 nanotubes are promising candidates for practical photochemical reactors.