Fabrication of a novel carbon quantum Dots-Modified 2D heterojunction for highly efficient sunlight photocatalysis

A novel carbon quantum dots- (CDs) modified 2D heterojunction photocatalyst was successfully fabricated by a facile impregnation and calcination approach. The results of photocatalytic experiments showed that the photocatalyst CDs/g-C₃N₄/MoS₂ exhibited tremendously enhanced photocatalytic activity. The rates for hydrogen evolution and degradation of rhodamine B (RhB) under simulated sunlight irradiation were about 5 and 7 times higher than those of pristine g-C₃N₄. Moreover, its photocatalytic activity was higher than those of g-C₃N₄/MoS₂, the benchmark reagent P25, and other heterojunctions reported previously. Heterojunctins loaded with different percentages of CDs by weight were synthesized and it was found that the heterojunctin with 2% of CDs showed the highest efficiency. The possible mechanism for enhanced activity was proposed. The great enhancement of photocatalytic activity could be ascribed to the CDs modification and the formation of the 2D heterojunction, which greatly facilitate the charge transfer at interfaces, reduce the recombination rates of photoinduced electron-hole pairs, and increase the light absorption. The results reveal that the construction of CDs-modified 2D heterojunction is a facile strategy to boost the sunlight-driven photocatalytic activity for semiconductor photocatalysts, facilitating their practical applications in environmental protection.