Graphitic carbon nitride-based materials for photocatalytic antibacterial application

The prevalence of bacterial infections and resistance to existing antibiotics make new effective antibacterial strategies urgently needed. Photocatalytic antibacterial, an effective strategy relying on exogenous excitation, has drawn increasing attention over the past decades, owing to its controllable, safe, and non-invasive characteristics. Many photoresponsive agents have been developed. With exceptional features of abundance, facile synthesis, suitable band structure, high stability, and low toxicity, metal-free polymeric two-dimensional nanomaterial graphitic carbon nitride (g-C₃N₄) is an attractive photosensitizer for antibiotic-free antibacterial application. In this review, the basic structural characteristics and preparation methods of g-C₃N₄ are summarized. The photocatalytic antibacterial mechanism of g-C₃N₄ through reactive oxygen species (ROS) generation is also discussed. In order to achieve more precise and efficient antibacterial effects, we pay special attention to two aspects: (1) how to increase the utilization of visible light and reduce the recombination of electron-hole pairs, thereby enhancing the production of ROS; and (2) how to obtain effective bacteria-killing activity while maintaining good biocompatibility and environmental friendliness, which determines the practical applications of materials. Several significant modification strategies are thus introduced, including structure design, surface modification, element doping, and construction of g-C₃N₄-based heterojunctions. Furthermore, various typical examples of combining the photocatalytic antibacterial effect of g-C₃N₄ with other strategies to exert good synergistic effects are summarized. Lastly, the potential challenges and perspectives are offered. This review is expected to inspire more follow-up work to design high-performance g-C₃N₄-based materials for photocatalytic antibacterial application.