1,3,5-Benzenetriyl substituted g-C3N4 for enhanced visible light photocatalytic activity

1,3,5-Benzenetriyl substituted g-C3N4 (BTCN) was prepared by copolymerizing dicyandiamide with 1,3,5-benzenetricarbonitrile, in which the bridge N-3C of g-C3N4 was substituted by the benzene moiety. A larger conjunction system thus forms between the benzene and the tri-s-triazine moieties. BTCN exhibits a narrowed band gap, obvious visible light absorption, and a promoted photogenerated charge separation. The visible light photocatalytic degradation rate of AO7 with 0.5% benzene substituted g-C3N4 is about 3.8 times higher than that with primary g-C3N4. The 0.5%BTCN exhibits excellent photostability for the cyclic photocatalytic degradation of AO7. The substitution of N-2C and N-C was also carried out by using isophthalonitrile and benzonitrile as the copolymerized precursors, respectively, which however show relatively weaker promotions to the photocatalytic performance of g-C3N4 than the substitution of N-3C with 1,3,5-benzenetriyl.