Enhanced Photocatalytic Activity of Lead-Free Cs2TeBr6/g-C3N4 Heterojunction Photocatalyst and Its Mechanism

In this study, a new type of lead-free double perovskite Cs 2 TeBr 6 combined with metal-free semiconductor g-C 3 N 4 heterojunction is constructed and used for photocatalytic CO 2 reduction for the first time. The S-scheme charge transfer mechanism between Cs 2 TeBr 6 and g-C 3 N 4 is systematically verified by X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR) and in situ Fourier infrared spectroscopy(FT-IR). The formation of S-type heterojunction makes the photocatalyst have higher charge separation ability and highest redox ability. The results show that 5%-CTB/CN heterojunction material has the best photocatalytic reduction effect on CO 2 under visible light irradiation. After 3 h of illumination, the yield of CO and CH 4 are 468.9 µmol g −1 and 61.31 µmol g −1 , respectively. The yield of CO is 1.5 times and 32 times that of pure Cs 2 TeBr 6 and g-C 3 N 4 , and the yield of CH 4 is doubled compared with pure Cs 2 TeBr 6 . However, g-C 3 N 4 almost does not produce CH 4 , which indicates that the construction of heterojunction helps to further improve the photocatalytic performance of the material. This study provides a new idea for the preparation of Cs 2 TeBr 6 /g-C 3 N 4 heterojunction and its effective interfacial charge separation.