Facile design of F-doped TiO2/g-C3N4 heterojunction for enhanced visible-light photocatalytic activity

To maximize the photocatalytic performance of practical energy devices, F-doped TiO2 particles are anchored on g-C3N4 nanosheets through the liquid phase deposition (LPD) and calcination process. The photocatalytic activity of F-doped TiO2/g-C3N4 (T-CN) composite is evaluated by the degradation of Rhodamine B (RhB) solution under visible-light illumination. The T-CN-300 sample (contain 300 mg g-C3N4) degrades 97% RhB after its illumination for 20 min. The quantum yield of the T-CN-300 sample is about three times higher than that of the pristine F-TiO2 and g-C3N4 samples. Moreover, the trapping experiments of the T-CN-300 sample indicate that the superoxide radical (center dot O-2(-)) is the main active species upon the photocatalytic process. The spin-trapping experiments confirm that the T-CN-300 sample can produce more center dot O-2(-) species than the other samples. The reduced interfacial charge transfer resistance of the T-CN-300 sample significantly enhances the photocurrent. The results reveal that the unique heterojunction of F-TiO2 and g-C3N4 can effectively separate the photogenerated electron-hole pairs, accelerate the photocatalytic reaction, and increase the center dot O-2(-) species in the photodegradation system.