Study on the synergistic performance of biomass carbon quantum dots and ultrathin g-C₃N₄ in efficient hydrogen peroxide production via photocatalysis

Hydrogen peroxide, as a clean energy source, plays a vital role in human production and daily life, as well as in ecological and environmental protection. This study reports the synthesis of ultrathin nanosheets of carbon nitride (CnCN) via multi-step pyrolysis and loading with biomass carbon quantum dots. Within 2.5 hours, the H2O2 yield reached 477.76 μmol·L−1, representing 2.19 times and 1.30 times higher than that of pristine graphitic carbon nitride (CN) and ultrathin nanosheets of graphitic carbon nitride (nCN), respectively. Characterization analysis reveals that the formation of ultrathin structures and the synergistic loading of biomass carbon quantum dots synergistically optimize the catalyst's specific surface area, band structure, and light absorption properties. This significantly enhances the separation of photo-generated electrons and holes, promoting electron migration from the bulk phase to surface active sites. Concurrently, the surface-loaded biomass carbon quantum dots act as electron capture and transport sites, accelerating electron transfer to surface-adsorbed oxygen. Mechanism investigations indicate that CnCN primarily generates hydrogen peroxide through a two-step single-electron oxygen reduction. This study provides new insights for the synergistic optimization of g-C3N4, offering a theoretical basis for achieving efficient hydrogen peroxide production and environmental protection.