Magnetic nitrogen-doped carbon nanofibers containing homogeneously dispersed CoFe2O4 nanoparticles with lightweight and efficient microwave absorption performance

Homogeneously dispersed ultrafine CoFe ₂O ₄ nanoparticles embedded within N-doped carbon nanofibers (named as CFO@NCNFs) have been fabricated via electrospinning and following heat treatment procedures. The dielectric and magnetic parameters of CFO@NCNFs/paraffin wax composites are regulated through adjusting the concentration of CoFe ₂O ₄ to obtain good impedance matching and excellent microwave absorption (MA) properties. Benefiting from the unique structure involving CoFe ₂O ₄ @onion-like carbon nanospheres and 3D conductive NCNFs network, as well as the synergistic mechanism between ultrasmall magnetic CoFe ₂O ₄ nanoparticles and light mass dielectric NCNFs. The CFO@NCNFs-5 exhibit outstanding MA properties at only 20 wt% filler loading and minimum reflection loss (RL) achieves −47.9 dB (surpass 99.9% MA) at 9.2 GHz with a thin thickness of merely 1.7 mm, and the corresponding effective absorption bandwidth (RL < −10 dB) achieves 5.4 GHz (6.5–11.9 GHz). Moreover, the effective absorption bandwidth (EAB) can be obtained in multiband (3.9–18.0 GHz) by adjusting the thickness of sample layer. Our work indicates that the appropriate incorporation of ultrafine CoFe ₂O ₄ nanoparticles encapsulated in NCNFs is a versatile and high-efficiency strategy to integrate lightweight and excellent properties of magnetic carbon-based absorbers.