Synthesis of Hierarchical CF@Fe₃O₄ Fibers Decorated with MoS₂ Layers Forming Core–Sheath Microstructure toward Tunable and Efficient Electromagnetic Wave Absorption

Hierarchical structural design has been verified as a feasible strategy to fabricate effective electromagnetic wave (EMW) absorbers, so we designed hierarchical core–sheath composites with magnetic particles and dielectric layers. In this work, a hierarchical structure of carbon fiber (CF)@Fe 3 O 4 @MoS 2 (CPDF7-M) was prepared by introducing Fe 3 O 4 and depositing MoS 2 layers on the surface of fibers. Due to the synergistic effects from the CF@Fe 3 O 4 increasing the conductive and magnetic loss and the outer MoS 2 layers improving the impedance matching, the optimal reflection loss ( R L ) value was −63.1 dB at 2.7 mm and the effective absorption bandwidth (EAB) was 9.1 GHz covering the X and Ku band. Moreover, the EAB values were adjusted with a specific MoS 2 loading at different thicknesses, which provided the necessary reference for the construction of efficient and flexible absorbers in the EMW absorption fields.