Abstract: The increasing concerns over electromagnetic (EM) pollution, military stealth technology, and microbial contamination necessitate the development of multifunctional materials that combine high-efficiency microwave absorption (MA) with robust antibacterial activity. However, achieving this integration remains challenging due to the conflicting requirements of conductivity, impedance matching, and surface functionality. Herein, a multilevel core-shell MXene@Fe₃O₄@ZnFe₂O₄@NC composite is designed and fabricated via a combined solvothermal and electrostatic self-assembly strategy. This unique architecture integrates a flexible conductive MXene substrate, hollow Fe₃O₄@ZnFe₂O₄ magnetic double-shell structures, and a nitrogen-doped carbon outer layer, introducing defect dipoles and optimizing impedance matching. Zn doping triggers electron redistribution, enabling precise tuning of EM parameters and enhancing interfacial polarization at the MXene/Fe₃O₄, Fe₃O₄@ZnFe₂O₄, and carbon/magnetic interfaces. The optimized composite exhibits an exceptional minimum reflection loss (RL_min) of -53.4 dB at 13.4 GHz and a broad effective absorption bandwidth (EAB) of 7.36 GHz at an ultrathin thickness of 1.9 mm. Radar cross-section (RCS) simulation further confirms its outstanding stealth performance. Moreover, the composite demonstrates superior antibacterial efficacy against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) under EMW irradiation, with lethality rates of 98.6% and 99.3%, respectively, arising from synergistic physical membrane damage from sharp MXene/NC edges and chemical damage from reactive oxygen species (ROS). This work provides a promising strategy for developing high-performance, multifunctional electromagnetic absorbing materials for next-generation portable electronics, medical devices, and radar stealth applications.

Key words: MXene, Electromagnetic wave absorption, Impedance matching, Core-shell structure, Antibacterial