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

<table>UV-vis diffuse reflectance spectra of N-TiO<sub>2</sub> and W-N-TiO<sub>2</sub>-X samples.</table>

International Journal of Photoenergy

Figure 4: Enhanced Visible Light Photocatalytic Activity for TiO<sub><b>2</b></sub> Nanotube Array Films by Codoping with Tungsten and Nitrogen 