Fig. 6. (Top) UV/vis diffuse reflectance spectra of C-I as-synthesized product (190 °C), and after calcination in air at 400, 450, and 500 °C. For comparison, commercial TiO2 P25 is shown. (Bottom) Modified UV/vis diffuse reflectance plot used to determine the indirect optical band gap of TiO2−xCx samples after being calcined in air at 400 °C (a) and 475 °C (b) prepared by method C-II, and 400 °C (c), 450 °C (d) and 500 °C (e) prepared by method C-III, (f) TiO2 Degussa (P-25).