Composition design and performance regulation of three-dimensional interconnected FeNi@carbon nanofibers as ultra-lightweight and high efficiency electromagnetic wave absorbers

Highly dispersed fine FeNi nanoparticles (NPs) encapsulated within carbon nanofibers ([email protected]) have been fabricated through electrospinning followed by preoxidation and carbonization processes. The influences of FeNi content and filler loading on the electromagnetic (EM) and microwave absorption (MA) properties of the [email protected]/paraffin wax composites are studied in detail. Benefitting from the special hierarchical microstructure including zero-dimensional [email protected] carbon core-shell NPs, one-dimensional CNFs with short carbon nanotubes protrusions and three-dimensional conductive network, as well as the synergistic effect between small-sized magnetic FeNi NPs and lightweight dielectric CNFs, the as-prepared [email protected] samples exhibit excellent MA performances at the ultralow filler loading, in which the [email protected] with a filling content of only 5 wt% possesses the strongest absorbing intensity and broadest effective frequency bandwidth primarily due to better balance between EM attenuation capability and impedance matching. The minimum reflection loss (RL) reaches −31.3 dB (more than 99.9% MA) at 16.3 GHz with a small thickness of 1.7 mm, and the maximum effective absorption bandwidth (RL < −10 dB) is up to 5.6 GHz (12.0–17.6 GHz) at 1.9 mm, which are superior to those of many previously reported magnetic carbon-based hybrid absorbers. Our results demonstrate that the proper incorporation of small-sized FeNi NPs into CNFs is an efficient and promising strategy to design lightweight and high-performance EM wave absorbers.