Axially oriented peapod-like Fe3C/Fe nanotubes encapsulated in electrospun N-doped carbon nanofibers for broadband microwave absorption covering the entire Ku-band
摘要
Integrating rationally designed magnetic nanostructures into dielectric matrices is a pivotal strategy for developing high-performance microwave absorption composites. Herein, we report a novel structural engineering approach to fabricate axially oriented peapod-like Fe3C/Fe nanotubes encapsulated in electrospun N-doped carbon nanofibers (Fe3C/Fe NT@NCFs) via a facile electrospinning-carbonization route. This bioinspired peapod architecture endows synergistic dielectric-magnetic loss and optimized impedance matching, critical for superior microwave absorption performance. The axially aligned hollow Fe3C/Fe nanotubes exhibit vortex-domain magnetism and shape anisotropy to enhane magnetic loss. Multiple heterointerfaces (Fe3C/Fe/NCFs) amplify defect-induced dipole polarization and interfacial polarization, while the one-dimensional electrospun NCFs form a robust three-dimensional conductive network to facilitate conductive loss and multiple microwave scattering. At a low 30 wt% filler loading, the Fe3C/Fe NT@NCFs achieve ultra-broad effective microwave absorption bandwidth (RL ≤ -10 dB) spanning 4–18 GHz with a tunable thickness of 1.5–4.0 mm. Notably, an ultrathin thickness of 2.0 mm delivers an effective absorption bandwidth (EAB) of 6.3 GHz (11.3–17.6 GHz) that nearly covering the entire Ku-band, along with a minimum reflection loss (RLmin) of -23.7 dB at 1.60 mm. This work provides a high-performance candidate for Ku-band stealth and a versatile structural design paradigm for magnetic carbon-based microwave absorption materials.