Intermediate-band semiconductors perform functions similar to natural photosynthesis by combining two photons to achieve a higher electron excitation. In this study, a strategy was developed to prepare a high oxygen-doped CeF3 (CeF3-O) nanomaterial that exhibits photocatalytic activity under visible/NIR light for the first time. The homogeneous doping oxygen atoms were verified to efficiently modify the band structure of CeF3. DFT calculation predicted the formation of an intermediate band within CeF3 upon homogeneous doping of O at interstitial sites. The interaction between F and O atoms generates an intermediate band, which divides the total bandgap of CeF3-O into two sub-bandgaps at about 1.7 eV and 2.9 eV, enabling CeF3-O photocatalysis under visible light and NIR light. Reflectance spectra evidenced that the same bandgaps exist. The photocatalytic activities of CeF3-O were tested by wavelength-controlled light. The rate constants of TC-HCl photodegrading under visible/NIR light are 12.85 × 10−3 min−1 and 1.28 × 10−3 min−1, respectively. The two-step electron transfer was also obviously confirmed in visible-light photocatalysis. In conclusion, the high oxygen doping builds a more applicable band structure of CeF3-O for photocatalytic performance, charge transfer and special light response for visible/NIR light.
