Fabrication and electromagnetic wave absorption properties of ANF/CoFe2O4 composite aerogels

To address the limitations of conventional microwave absorbers, such as high density, inferior mechanical stability, and narrow effective absorption bandwidth, aramid nanofibers (ANF) were employed as the three-dimensional skeleton, and spinel CoFe 2 O 4 nanoparticles served as the magnetic loss component. A series of ANF/CoFe 2 O 4 composite aerogels with different particle loadings (15 wt%, 25 wt%, 35 wt%, 45 wt%) were fabricated via deprotonation exfoliation, surface modification, solvothermal reaction, and freeze-drying routes. The microstructure, phase composition, chemical valence states, and electromagnetic parameters were systematically characterized. The results show that CoFe 2 O 4 nanoparticles are uniformly anchored on the ANF network with favorable crystallinity and stable elemental valence. With increasing loading, the dielectric permittivity rises first and then declines, while the magnetic permeability increases monotonically. The 25 wt% sample achieves optimal dielectric-magnetic impedance matching. At a matching thickness of only 3.32 mm, its minimum reflection loss reaches −50.71 dB, and the effective absorption bandwidth is 4.73 GHz, covering the X–Ku bands. The excellent absorption performance originates from the synergistic effect of multi-scale scattering in the porous network, enhanced interfacial polarization, and combined dielectric–magnetic loss. This lightweight and robust ANF-based aerogel provides a promising candidate for high-efficiency electromagnetic wave absorption materials.