Nanofiber-reinforced CoFe₂O₄/graphene composite aerogel as broadband electromagnetic wave absorber

Graphene aerogel (GA) is a promising lightweight and high-performance material for electromagnetic wave absorption due to its ultra-light mass. However, the impedance matching and attenuation capabilities of GA are limited by its high conductivity and constrained attenuation paths. To address this limitation, magnetic materials are often combined with GA to enhance both impedance matching and attenuation performance. Nevertheless, little attention has been given to the influence of magnetic materials with varying morphologies on the electromagnetic wave absorption (EMA) properties. In this study, CoFe₂O₄ nanofibers were prepared via electrospinning technology as an alternative to commercial CoFe₂O₄ nanoparticles. Subsequently, CoFe₂O₄@GA composites were synthesized through a hydrothermal reaction in a graphene oxide (GO) solution. Moreover, the inclusion of ethylene glycol in the GO solution helped regulate the volume shrinkage of GA after the adding of CoFe₂O₄, thus preventing structural instability and fragmentation. The introduction of a small quantity of magnetic nanofibers significantly enhanced the EMA performance of the CoFe₂O₄@GA composite, increasing the strongest absorption from –34.5 to –53.5 dB and widening the maximum effective absorption bandwidth (EAB) from 8.0 to 8.7 GHz. Finally, the study revealed that CoFe₂O₄ nanofibers outperformed nanoparticles in electromagnetic wave loss mechanisms, including magnetic coupling, magnetic resonance, eddy current loss, and interface polarization. This finding provides valuable insights for the selection and optimization of magnetic component morphologies in EMA materials.