Multidimensional Magnetic Fillers of Co/MXene and CoFe2O4/Carbon Nanofibers Reinforced Polyimide Composite Aerogels toward Lightweight Electromagnetic Wave Absorption and Thermal Insulation

Achieving low reflection loss, broad absorption bandwidth and lightweight remains a major challenge for electromagnetic wave absorption (EWA) materials. In this work, the lightweight multifunctional polyimide composite aerogels reinforced with two-dimensional Co-anchored MXene (Co/MXene) and one-dimensional CoFe 2 O 4 -decorated carbon nanofibers (CoFe 2 O 4 /CNF) were successfully prepared for high-performance EWA. The dielectric and magnetic losses were significantly improved due to the unique heterogeneous porous structure in the composite aerogels. The aerogels achieve a minimum reflection loss of -59.4 dB at 7.6 GHz with a thin thickness of 2.31 mm, and the effective absorption bandwidth could be 4.24 GHz with an ultrathin thickness of 1.25 mm. The outstanding EWA performance can be attributed to the synergistic contribution of conductive loss, interfacial polarization loss, dipole polarization loss and magnetic loss. Moreover, the porous PI framework plays a crucial role in optimizing impedance matching and structural stability. The composite aerogels also demonstrate potential for radar stealth and thermal insulation. This work presents a new strategy for designing multifunction EWA materials.