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

Abstract 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.