Fabrication of macroporous magnetic carbon fibers via the cooperative etching-electrospinning technology toward ultra-light microwave absorption

Lightweight characteristics and high-efficiency absorption performance are two essential factors for microwave absorbents in practical applications, but still face considerable conflicts. Herein, we propose the cooperation of etching and electrospinning technology to construct macroporous magnetic carbon fibers (MMCFs) that simultaneously tackle the conflicts associated with lightweight characteristics and superior absorption performance. Specifically, ZIF-67 nanocubes are firstly etched into hollow structure and efficiently embedded into PAN fibers by electrospinning, the obtained fibers are transformed into MMCFs via the subsequent pyrolysis, in which inner hollow ZIF-67 nanocubes are converted into macroporous magnetic nanocubes and PAN fibers are carbonized into carbon fibers. Benefiting from the cooperative advantages of hollow macroporous cavity, conductive networks and dielectric-magnetic synergistic effect, the fabricated MMCFs exhibit superior microwave attenuation compared with most reported metal-organic-frameworks derivatives at an ultralow filler loading of 5 wt%. The maximum absorption intensity promises a high value of −49.4 dB and the effective bandwidth achieves 10.8 GHz. This work overcomes the vital limitation associated with lower filler loading of MOFs derived absorbents, and inspires us a new prospect to develop ultra-light absorbents in satisfying the electromagnetic protection demand.