Intrinsic cyano defects promoted exciton dissociation in cross-linked carbon nitride for boosting photocatalytic H2 and H2O2 generation

Carbon nitride has emerged as one of the most popular polymeric photocatalysts. However, it usually exhibits moderate photocatalytic activity due to the sluggish free-electron transport and rapid charge recombination. In this work, a cross-linked carbon nitride with abundant cyano defects was prepared by a molten-salt-assisted calcining method using disordered carbon nitride as the precursor. The cross-linking serves as inter-chain charge transport paths. Meanwhile, the numerous cyano defects can act as electron accepting sites, weakening the attraction between the electron and hole inside the exciton and then promoting the dissociation of excitons into free charges. The synergistic effect of rich cyano defects and cross-linked structure enables boosting generation and transport of free charge carries. Therefore, excellent photocatalytic performance for both H2 and H2O2 production are achieved. In comparison to those of traditional carbon nitride, the H2 and H2O2 production rates have increased 43 and 85 times, respectively.