Preparation of a Cu2O/g-C3N4 heterojunction with enhanced photocatalytic antibacterial activity under visible light

In this study, a Cu2O/g-C3N4 nanocomposite was prepared through in situ growth of Cu2O nanoparticles on g-C3N4 nanosheets. Subsequently, the antibacterial activities of Cu2O, g-C3N4 and Cu2O/g-C3N4 composites against Staphylococcus aureus and Pseudomonas aeruginosa were studied, respectively. The results show that the minimum bacteriostatic concentration of the composite is significantly smaller than that of Cu2O and g-C3N4 alone, and it also has better long-term bacteriostatic effect. The bacteriostatic effect of the prepared Cu2O/g-C3N4 nanocomposites is further enhanced by visible light irradiation. The first-principles calculation based on density functional theory (DFT) was used to obtain the work function of the composite materials. The Cu2O/g-C3N4 composite has a work function that is significantly lower than that of Cu2O and g-C3N4. The lower work function is beneficial to the separation of electrons and holes and the formation of reactive oxygen species (ROS) on the surface of the material, further reducing photocorrosion. This also explains the reason why the composite material has high bacteriostatic efficiency and better bacteriostatic effect. In addition, the calculation of the differential charge shows that the Cu atom near the heterojunction interface has a strong positive charge, which makes it more difficult to cause redox reactions and enhances the long-acting effect of the bacteriostatic agent. Therefore, based on our experimental and theoretical calculation results, the Cu2O/g-C3N4 composite has a broad application prospect in the field of photocatalytic bacteriostasis.