An Overview: Recent Development of Titanium Oxide Nanotubes as Photocatalyst for Dye Degradation
Figure 7
Various schemes illustrating the possible band gap electronic structure and excitation processes of visible-light-responsive TiO2 materials: (a) pure TiO2; (b) band gap narrowing model for nonmetal-doped TiO2; (c) oxygen-deficient TiO2; (d) localized mid-gap level model for nonmetal-doped TiO2; (e) oxygen vacancy and nonmetal-doped mid-gap levels are considered together [41].
