Facile synthesis of porous graphitic carbon nitride modulated by up-conversion carbon quantum dots for visible light-triggered photocatalysis towards bacteria inactivation

In this work, novel porous g-C3N4 nanosheets modulated by up-conversion carbon quantum dots (CQDs/CNS) were successfully fabricated. Using the photocatalytic inactivation of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) as the model reaction, the visible light-triggered antibacterial activity was evaluated. It was found that the photocatalytic performance towards bacterial inactivation is significantly improved, with the minimum inhibitory concentration (MIC) in CQDs/CNS against E. coli and S. aureus only being 12.5 and 40 ppm, respectively. The enhancement in antibacterial behavior can be attributed to the introduction of up-conversion CQDs. On the one hand, it extends absorption region to the visible light which promotes the generation of e- - h+ pairs. On the other hand, it narrows the energy band gap which accelerates the separation of carriers and transferance of charges at the interface. This study provides a new insight for developing a CQDs-based g-C3N4 system for effective bacterial disinfection.