High-Efficiency Photodynamic Antibacterial Activity of NH₂-MIL-101(Fe)@MoS₂/ZnO Ternary Composites

Bacterial infections are a serious threat to human health, and the development of effective antibacterial agents represents a critical solution. In this study, NH₂-MIL-101(Fe)@MoS₂/ZnO ternary nanocomposites are successfully prepared by a facile wet-chemistry procedure, where MoS₂ nanosheets are grown onto the MIL-101 scaffold forming a flower-like morphology with ZnO nanoparticles deposited onto the surface. The ternary composites exhibit a remarkable sterilization performance under visible light irradiation toward both Gram-negative and Gram-positive bacteria, eliminating 98.6% of Escherichia coli and 90% of Staphylococcus aureus after exposure to visible light for 30 min, a performance markedly better than that with NH₂-MIL-101(Fe)@MoS₂ binary composites and even more so than MoS₂ nanosheets alone. This is ascribed to the unique electronic band structure of the composites, where the separation of the photogenerated carriers is likely facilitated by the S-scheme mechanism in the NH₂-MIL-101(Fe)@MoS₂ binary composites and further enhanced by the formation of a p-n heterojunction between MoS₂ and ZnO in the ternary composites. This interfacial charge transfer boosts the effective production of superoxide radicals by the reduction of oxygen, and the disproportionation reaction with water leads to the formation of hydroxy radicals, as attested in spectroscopic and microscopic measurements. Results from this study highlight the significance of structural engineering of nanocomposites in the manipulation of the electronic band structure and hence the photodynamic activity.