Hierarchically Structured MnO2/Magnetic Nanofiber Composites for Efficient Electromagnetic Wave Absorption and Corrosion Shielding

To mitigate electromagnetic pollution resulting from the rapid development of high-speed communication technologies, such as 5G, it is crucial to develop composite materials that combine efficient electromagnetic wave absorption (EMA) performance with environmental stability. The synergistic interactions of multifunctional components and the construction of heterogeneous interfaces are recognized as effective strategies for enhancing both the EMA capability and corrosion resistance. In this study, a mesoporous magnetic composite material was successfully synthesized, Co/NC/CNFs@MnO2 (CNCM), by in situ growing a layered MnO2 structure on the surface of ZIF-67-derived magnetic carbon nanofibers. The material achieved a minimum reflection loss (RLmin) of −74.32 dB at a matching thickness of 2.17 mm and a maximum effective absorption bandwidth (EABmax) of 6.16 GHz (10.76–16.92 GHz) of 2.04 mm. This exceptional performance arises from the synergistic effects of conductive loss, dipole polarization, interface polarization, and magnetic loss, which enhance the loss mechanisms and optimize impedance matching, thereby improving electromagnetic wave (EMW) attenuation and energy conversion efficiency. HFSS simulations further confirmed its potential for electromagnetic stealth applications, demonstrating a significant reduction in radar cross-section (RCS) of 26.8 dB·m2 at vertical incidence and up to 46.0 dB·m2 at a 45° incidence angle, indicating an excellent infrared stealth performance. Additionally, the layered MnO2 structure acts as a physical barrier, effectively preventing the penetration of corrosive media and significantly enhancing the material’s corrosion resistance. This study provides valuable insights into the design of lightweight, efficient, and corrosion-resistant electromagnetic protective materials.