Enhanced Visible Light Photocatalytic Activity for TiO<sub><b>2</b></sub> Nanotube Array Films by Codoping with Tungsten and Nitrogen

<table>XRD patterns of N-TiO<sub>2</sub> and W-N-TiO<sub>2</sub>-X (a), the enlarged XRD peaks of crystal plane (101) (b). </table>

International Journal of Photoenergy

Figure 1: Enhanced Visible Light Photocatalytic Activity for TiO<sub><b>2</b></sub> Nanotube Array Films by Codoping with Tungsten and Nitrogen 