Integrating N/S codoping with a multi-heterointerface Fe7S8/Fe2S/Fe3C@C porous carbon composite with microwave absorption and antibacterial bifunctions

Heterointerface engineering has been widely proven effective for designing composite materials with high-efficiency microwave absorption (MA) capabilities. However, challenges persist in regulating the interface structures of MA materials at the microscale and nanoscale. In this study, a novel N/S-codoped multi-interfacial porous carbon composite (Fe 7 S 8 /Fe 2 S/Fe 3 C@C) is successfully prepared by chemical foaming and vulcanization. Concretely, when the carbonization and vulcanization temperature were both 600 °C, the mass ratio of carbonized sample to sulfur (carbon: sulfur) was 1:2 (PF-2), which exhibited exceptional electromagnetic wave attenuation properties. Notably, the composite achieved a minimum reflection loss ( RL min ) of −48.83 dB at 1.85 mm thickness, and an effective absorption bandwidth (EAB) value reaching 6 GHz (12–18 GHz) at 2 mm, while the proportion of paraffin wax was only 20 wt%. The significantly improved MA performance primarily originated from the synergistic effects between dielectric/magnetic heterostructures and heterointerfaces. In addition, PF-2 exhibits excellent antibacterial properties, with antibacterial rates against Escherichia coli and Staphylococcus aureus both exceeding 99.999 % under no light and 808 nm light conditions. Overall, this research provides a pathway through heterointerface engineering for designing a new generation of multifunctional electromagnetic wave absorbing materials.