Bottom-Up Synthesis\nof High-Entropy Alloy/Carbon Nanofiber\nwith Magnetic–Dielectric Synergy for Low-Filler and Broadband\nElectromagnetic Wave Absorption

Rational design of the composition and microstructure\nhas been\nrecognized as an effective strategy for fabricating high-efficiency\nelectromagnetic wave (EMW) absorption materials. Herein, hierarchical\nFeCoNiMnCu high-entropy alloys (HEAs)/carbon nanofiber (FeCoNiMnCu/CNF)\ncomposites were fabricated by using a bottom-up synthesis method involving\nelectrospinning followed by calcination. The nanosized FeCoNiMnCu\nnanoparticles are uniformly embedded within the CNF, constructing\npartial core–shell structures and abundant interfaces. Adjusting\nthe calcination temperature can effectively regulate the crystallinity,\ngraphitization degree, and electromagnetic parameters. The FeCoNiMnCu/CNF\ncomposites exhibit excellent EMW absorption performance, with strong\nabsorption of −64.4 dB and broadband absorption of 4.1 GHz\nat a low filling of 10 wt % and thin thickness at 1.9 mm. Conductive\nloss, interface polarization, eddy current loss, and magnetic–dielectric\nsynergy of FeCoNiMnCu/CNF composites collectively contribute to the\nsuperior EMW absorption performance. This study underscores the great\npotential of bottom-up synthesis in combining HEAs with CNF to develop\nlow-filling and broadband HEA-based EMW absorption materials.