The Carbon dot/TiO2 catalyst overcomes the problem of the short excited state lifetime of carbon quantum dots and has a good catalytic effect under the irradiation of blue or green light. Lu Xu modified carbon quantum dots on N-doped TiO2 and prepared C-N-TiO2-x composite material, and found that this material has stronger visible light absorption capacity and higher charge separation efficiency than TiO2 without N or carbon quantum dots. In addition, adding an appropriate amount of citric acid to remove holes can significantly increase the reduction rate of Cr (VI). More research on metal-modified TiO2, such as Pd/TiO2 , Au/TiO2 , Pt/TiO2 showed their great significance photocatalytic oxidation of aromatic alcohols.