Figure 4From: Growth and characterization of TiO2 nanotubes from sputtered Ti film on Si substrateDiffuse-reflectance UV–vis spectroscopy. The T-NT on Si after anodization at 10 to 60 V and annealing in air at 350 °C. The anodization time was 1 h. The band gap was about 3.4 to 3.25 eV.Back to article page