In-situ growth of core-shell CoFe@CoFe2O4 nanoparticles on carbon aerogel for broadband electromagnetic wave absorption and thermal insulation

The composite engineering of dielectric-magnetic systems has demonstrated significant potential for enhancing the electromagnetic wave absorption (EWA). Despite advances, achieving uniform in-situ growth of highly dispersed magnetic particles on carbon matrices remains technologically challenging. This study proposes an integrated freeze-drying and carbonization strategy, successfully fabricating CoFe@CoFe 2 O 4 /C aerogel, featuring carbon nanosheets uniformly decorated with in-situ grown core-shell magnetic particles. The carbon aerogel annealed at 700 °C exhibits exceptional impedance matching and EWA characteristics, achieving an ultrawide effective absorption bandwidth of 7.84 GHz (10.16–18 GHz) at an optimized thickness of 2.63 mm. The outstanding absorption performance is attributed to the electromagnetic coupling between core-shell magnetic architectures and conductive carbon networks. First-principle calculations reveal dielectric polarization loss arising from interfacial heterogeneities and defect engineering in aerogels. Simultaneously, the hierarchical porosity endows the aerogel with superior thermal insulation. These integrated attributes position the aerogel as a multifunctional platform for EWA applications and advanced radar-infrared compatible stealth systems.