Interface‐Engineered C ₃ N ₄ /TiN Heterostructures for Synergistic Photocatalytic‐Nanozyme ROS Generation and Anti‐Infective Therapy

ABSTRACT Bacterial infections have become a serious public health concern, highlighting the urgent need for efficient and safe antibacterial strategies. Functional heterostructure materials combining photocatalytic and nanozyme activities hold great potential for developing novel antibacterial therapies. In this study, ultrasonically exfoliated two‐dimensional (2D) CN (CN) nanosheets were employed as a substrate to uniformly load ultrasmall TiN (TN) nanoparticles, forming C 3 N 4 /TiN (CNT) heterojunctions. The introduction of TN increased the specific surface area, stabilized the interface, and induced significant charge redistribution and orbital hybridization, thereby enhancing the separation and transport of photogenerated carriers and improving photocatalytic reaction kinetics. Peroxidase‐like activity evaluation revealed that CNT exhibited markedly accelerated H 2 O 2 decomposition under light, with lower reaction barriers, strong reactive oxygen species generation, and high substrate affinity. Benefiting from the synergistic effect of photocatalysis and nanozyme activity, the material efficiently killed chloramphenicol‐resistant Escherichia coli and methicillin‐resistant Staphylococcus aureus (MRSA) in vitro, disrupted bacterial structures, and inhibited biofilm formation. In vivo, the system achieved nearly complete bacterial clearance, promoted inflammation resolution, collagen deposition, and epidermal regeneration, enabling wound healing within nine days. This work reports a scalable, safe, and effective photocatalytic–nanozyme antibacterial platform for treating refractory skin infections.