FeS ₂ /WS ₂ Heterostructure: A Promising Candidate for Mild‐Temperature Photothermal Therapy with Enhanced Photodynamic Effect and Antibacterial Activity

Abstract FeS 2 , a member of metal chalcogenide semiconductors, is a cheap and available material with distinguishable photothermal activity under light irradiation. However, its photodynamic properties have to be improved for practical phototherapy applications. Therefore, in this study, FeS 2 /WS 2 p‐n junctions, comprising varying amounts of WS 2 , are synthesized using the simple hot injection method. Establishment of the heterostructure is verified using X‐ray diffraction (XRD), scanning transmission electron microscopy (STEM), energy‐dispersive X‐ray spectroscopy (EDX), and X‐ray photoelectron spectroscopy (XPS) analysis. p‐n junction formation is further validated via calculations based on ultraviolet‐visible (UV–vis.) spectrophotometer and XPS data. Photothermal and photodynamic properties of the samples are examined considering various aspects. The FeS 2 /WS 2 heterostructure provides a heating response above 50 °C with a high photothermal conversion efficiency of 52.6%. The reactive oxygen species (ROS) formation ability is observed to depend on the material concentration and O 2 • ‾ is determined as the primary reactive oxygen species. The in vitro antibacterial activity of the samples is tested against Staphylococcus aureus ( S. aureus ) and Escherichia coli ( E. coli ) bacteria as a function of material concentration. At all concentrations, the FeS 2 /WS 2 heterostructure exhibits higher activity than that of FeS 2 nanoparticles. The efficiency of the sample against S. aureus and E. coli is calculated to be 100% and 99.4% respectively, at a low material concentration of 100 µg mL −1 .