Fabrication of visible-light responsive S-F-codoped TiO2 nanotubes

Fabrication and S-F-codoping of TiO₂ nanotubes were carried out by a one-step electrochemical anodization process to extend the photoresponse of TiO₂ to the visible-light region. The prepared samples were annealed in air and detected by SEM, XRD, XPS and UV-vis DRS spectrophotometer. The results showed that the average tube diameter of the nanotubes was 150 nm and the average tube length was 400 nm. The doped TiO₂ nanotubes exhibited strong absorption in visible-light region. Photoelectrocatalytic degradation efficiency of 4-CP over S-F-codoped TiO₂ nanotubes was 39.7% higher than that of only-F-doped sample. Moreover, sulfur and fluorine codoped into substitutional sites of TiO₂ had been proven to be indispensable for strong response and high photocatalytic activity under visible light, as assessed by XPS. Supported by the National Natural Science Foundation of China (Grant Nos 90610005, 20576120, 20336030 and U0633003), the National “863” Program (Grant No. 2007AA06Z339), and Science and Technology Bureau of Zhejiang Province (Grant No.2007C13061)