Photocatalytic degradation of MB by TiO2, T-5, T-10, and T-15was performed under visible light irradiation, as shown in Fig. 8.The normalized temporal concentration changes (C/C0) of MBduring the photocatalytic process are proportional to the normal-ized maximum absorbance (A/A0), which can be derived from thechanges in the MB absorption profile at a given time interval. Itis observed that the concentration of MB is hardly reduced undervisible light irradiation in the absence of the photocatalyst. F-TiO2exhibits better photocatalytic performance than pure TiO2. Thephotocatalytic performance of F-TiO2depends on the F dopingconcentration. The degradation rate of MB for pure TiO2is 32%.When F is doped into TiO2, the degradation rate is increased to67% for T-5, and reaches a maximum value of 91% for T-10. TheFig enhancement of photocatalytic performance should be ascribedto the increase in the visible light absorption and the reductionin electron-hole pair recombination in TiO2with the F doping,which has been confirmed from the absorption and EIS spectra. Inaddition, the oxygen vacancies can act as new active sites to reduceO2and form superoxide radicals and hydroxyl radicals, which isresponsible for photocatalytic degradation of organic pollutants