Mechanism analysis of surface structure-regulated Cu₂O in photocatalytic antibacterial process

The effects of exposing crystal planes and vacancy defect engineering can induce unique surface atom arrangements that strongly influence the physicochemical properties of semiconductor materials. This paper used Cu₂O with different surface structures as a research model. A liquid-phase method was chosen for surface structure regulation to prepare Cu₂O semiconductors (Vo-(111)Cu₂O, Vo-(100)Cu₂O, Vo-(110)Cu₂O) with different exposed crystalline surfaces analyze the antibacterial mechanisms of other faceted models in the photodynamic antibacterial process. The bactericidal effect of Vo-(111)Cu₂O (40 μg/mL, 100%) was better than that of Vo-(100)Cu₂O and Vo-(110)Cu₂O. DFT simulations show that the photocatalytic antimicrobial performance of Vo-(111)Cu₂O is improved due to surface defect structures caused by unsaturated coordination bonds and suspension bonds on its exposed crystalline surfaces. The suspension bonds act as active centres for trapping electrons, leading to a lower carrier complexation rate on the material surface. The antibacterial mechanism of Vo-(111)Cu₂O showed that oxidative sterilization by reactive oxygen species (ROS) was the dominant factor (61.98%) in the antibacterial process. The most potent depolarizing effect on E. coli, the highest copper ion solubilization, and the highest ROS yield. Therefore, ROS oxidative sterilization, copper ion leaching sterilization, and contact damage synergistically affect E. coli from the inside out.