Creating dual charge transfer channels to collaborative enhance the photocatalytic bacteriostatic efficiency and photocorrosion resistance of Cu2O based nanocomposites

Abstract

Cuprous oxide (Cu2O), as one of the traditional photocatalytic antifouling agents, has its own defects for practical applications such as rapid recombination of carriers, serious photocorrosion (Cu2O changing into CuO) and explosive release of cuprous ions. Herein, a novel ternary interfacial heterojunction (Cu2O/C/CCN) was prepared by carbon doping of g-C3N4 followed by in-situ carbon film covering and Cu2O loading. Compared with pure Cu2O and Cu2O/g-C3N4, Cu2O/C/CCN presented more powerful broad-spectrum and long-term photocatalytic antibacterial properties against S. aureus and P. aeruginosa, and the antibacterial rate remained at approximately 94.28% and 90.54%, respectively, even after storage 30 days. The high antibacterial rate of the Cu2O/C/CCN can be attributed to the high photocatalytic performance and stable and continuous release of cuprous ions. The carbon doping of g-C3N4 could adjust its band gap and promote more efficient photoexcited carrier generation and transfer by the formation of delocalized large π bonds like “electron bridge” as the first charge transfer channel. The existence of carbon film between g-C3N4 and Cu2O can build the second highly efficient charge transfer channel for the separation of photoexcited carriers by forming a Z-scheme interfacial heterojunction. DFT calculation and fluorescence spectrum results showed that more active electrons on CCN tend to transfer to Cu2O through the two nonradiative decay pathways. The highly efficient carrier transport and separation can also greatly reduce the 15.3% generation of CuO compared to Cu2O/g-C3N4. The more negative reduction potential further promoted the ROS generation for sterilization. In addition, the loading of Cu2O on 2D C/CCN can reduce the contact area between Cu2O and solution and then slow the release rate of cuprous ions by 75% compared to Cu2O. Therefore, Cu2O/C/CCN has great potential for practical antifouling applications.