Axially Oriented Magnetic-Carbon Fibers via Confined Electrospinning for Tunable Broadband Electromagnetic Wave Absorption.

Wide-frequency response in electromagnetic (EM) wave absorption materials usually depends on the composition ratio or macro-structure design. How to achieve axial orientation arrangement of magnetic nanoparticles in 1D carbon fibers faces huge challenges. In this work, axially oriented magnetic-carbon (Fe@NC) fibers are fabricated via confined electrospinning and pyrolysis, where spindle-shaped Fe nanoparticles (NPs) are in situ confined within carbonized PAN fibers with their axial direction aligned along the fiber orientation, forming a synergistic heterostructure. Aligned Fe@NC fibers enhanced anisotropy and assembled 3D fiber network boosted electron transfer and magnetic coupling, co-contributing to the energy dissipation. And the micromagnetic simulations revealed the evolution of magnetic domains with increasing magnetic Fe NPs. Benefiting from the dielectric-magnetic synergy, the optimized Fe@NC composite achieved exceptional broadband EM wave absorption, exhibiting an ultra-wide effective absorption bandwidth (EAB) of 7.1 GHz (covering the entire Ku-band) at a thin thickness of 1.7 mm. This work provides a novel strategy for designing wide-frequency absorbers and advances the controllable synthesis of 1D axially oriented magnetic-dielectric functional composites.