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

Abstract

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.