Hydrochloric-acid-induced hydrothermally pretreated ultrathin C3N4 nanosheets for efficient photocatalytic H2 evolution

BACKGROUND C 3 N 4 nanosheets with a layered structure have attracted significant interest in the field of photocatalysis. However, direct preparation of these nanosheets remains a significant challenge. RESULTS In this study, highly active C 3 N 4 nanosheets were fabricated via the direct thermal polymerization of melamine supramolecular aggregates obtained using hydrochloric-acid-induced hydrothermal pretreatment. Various methods were adopted to characterize the photocatalytic materials obtained and density functional theory calculations were performed to understand the highly efficient nature of C 3 N 4 . The structures and photochemistry of the photocatalytic materials depend on the hydrochloric-acid-induced hydrothermal pretreatment method. It was found that C 3 N 4 -180-H nanosheets have numerous (C) 2 N–H that are conducive to photogenerated electron–hole separation. In addition, the C 3 N 4 -180-H nanosheets have a large surface area and a short charge-carrier diffusion distance. Furthermore, the C 3 N 4 -180-H nanosheets exhibited a longer excitation-state charge-carrier lifetime than bulk C 3 N 4 . The as-prepared C 3 N 4 -180-H nanosheets with unique structural advantages showed superior photocatalytic H 2 evolution performance (413 μmol h −1 g −1 ) compared to that of bulk C 3 N 4 (90.5 μmol h −1 g −1 ). CONCLUSION This study offers a feasible and simple method for synthesizing C 3 N 4 nanosheets and developing an excellent 2D photocatalyst for superior solar-to-H 2 production. © 2023 Society of Chemical Industry (SCI).