Embedding carbon quantum dots into the g-C3N5 composite for boosting photocatalytic hydrogen production performance

Morphological engineering and composite fabrication of graphitic carbon nitride (g-C 3 N 5 ) are effective strategies to suppress photogenerated charge carrier recombination, improve electronic conductivity, and optimize photocatalytic performance. This research significantly enhanced the photocatalytic hydrogen evolution performance of g-C 3 N 5 through morphology regulation and carbon quantum dot (CQDs) compositing strategies. Using 3-amino-1,2,4-triazole as the precursor, thin-layered g-C 3 N 5 is prepared via thermal polymerization and KOH exfoliation, and CQDs are in-situ composited via a hydrothermal method. The optimized g–C 3 N 5 –1.0% composite is a S-Scheme heterojunction, featuring a narrow band gap (2.12 eV), a more negative conduction band position, and excellent charge separation efficiency. Under visible light, it achieves a hydrogen evolution rate of 2.9 mmol/g/h, which is 9.7 times that of pure g-C 3 N 5 , along with good cycling stability. This study provides a feasible strategy for developing high-efficiency non-metallic photocatalysts.