Enhanced LED light-driven antibacterial system with efficient charge transfer coordinated by Bi2WO6/TiO2 Z-scheme heterojunction

Designing efficient antimicrobials for the rapid disinfection of water is increasingly critical owing to the rising threat of pathogenic microorganisms. In this study, direct Z-scheme Bi 2 WO 6 /TiO 2 heterojunctions were constructed using a simple in situ hydrothermal method. The optimal Bi 2 WO 6 /TiO 2 Z-scheme heterojunction inhibited 98.80 % of Escherichia coli (5 × 10 8  CFU mL −1 ) at 0.35 mg mL −1 and 99.33 % of Staphylococcus aureus (5 × 10 8  CFU mL −1 ) at 0.5 mg mL −1 after 10 min of light-emitting diode (LED) light irradiation. Furthermore, in antibiotic degradation experiments, Bi 2 WO 6 /TiO 2 had a 92.91 % removal rate for ciprofloxacin with a pseudo-second-order degradation rate constant ( k ) of 0.056 min −1 after 240 min of irradiation. The antibacterial mechanism of Bi 2 WO 6 /TiO 2 was systematically investigated and confirmed to occur by LED light-driven surface activation and efficient charge transfer. The surface and interfacial structures of the Bi 2 WO 6 /TiO 2 samples were studied by high-resolution transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The antibacterial mechanism was studied by controlled experiments and electron spin resonance analyses, which revealed that the primary antibacterial mechanism of Bi 2 WO 6 /TiO 2 is oxidative sterilisation via generated reactive oxygen species. Time-resolved fluorescence spectroscopy was used to analyse the charge-transfer pathway in Bi 2 WO 6 /TiO 2 , which demonstrated that the spatial separation of the redox-active sites extended the lifetimes of the photogenerated carriers, enhancing the oxidative destruction of bacteria. This comprehensive understanding paves the way for the design of new Z-type heterojunction photocatalytic materials for antimicrobial applications.