Lightweight Fe3O4/Fe/C/rGO multifunctional aerogel for efficient microwave absorption, electromagnetic interference shielding, hydrophobicity and thermal insulation

Effective integration of multiple functions into microwave absorbing materials is a future development direction, but still remains a significant challenge. This work fabricated a lightweight, multifunctional aerogel through electrostatic self-assembly, freeze-drying and in-situ pyrolysis process, achieving an in-situ composite of magnetic/dielectric components. The regulated pyrolysis temperature achieves a good balance between abundant nanopores and heterogeneous interfaces, enriched defects, and conductivity. This balance induced a synergy of dielectric loss, magnetic loss, and conduction loss at low frequencies, improving the impedance matching. The aerogel obtains a minimum reflection loss (RL min ) of −65.17 dB in the low-frequency range and a maximum effective absorption bandwidth (EAB max ) of 5.76 GHz. The radar cross section (RCS) simulation confirmed its good stealth performance. In addition, an increase in aerogel loading enhanced its electrical conductivity, resulting in a higher electromagnetic interference (EMI) shielding effectiveness (SE) of 81.83 dB, the specific shielding effectiveness (SSE) up to 359.28 dB·cm 3 /g and the absolute shielding effectiveness (SSE t ) up to 1596.82 dB·cm 2 /g. Beyond microwave absorption and shielding, this aerogel also exhibited good hydrophobicity and thermal insulation. This study provides a new perspective for the development of materials with microwave absorption properties in low-frequency bands and multifunctional properties for broader applications in military, communication, aerospace, and other fields.