Modulation of carbon atom hybridization structure and electromagnetic absorption properties in carbon fiber composites

Abstract

Carbon fiber composites exhibit significant potential for electromagnetic wave (EMW) absorption, whereas the practical application is limited by excessive electrical conductivity and a single loss mechanism. Herein, high-entropy borate (HE ReBO₃) loaded carbon fiber composites were fabricated by electrospinning, which the fiber morphology and sp²/sp³ hybridized carbon ratios were controlled by borate loading. The results show that the sp² hybridization carbon ratio increased from 24.28 % to 29.08 %, intensifying dipole polarization loss. Meanwhile, the introduction of HE ReBO₃ induced a ribbon-like fiber structure with median diameters of 0.57 μm, which enhanced multiple reflection/scattering of EWM and interface polarization. The synergistic effect between dipole and interface polarization endowed the composite with exceptional absorption properties. The optimal composite (HE ReBO₃-3) achieved a minimum reflection loss (RL_min) of −59.41 dB at 2.18 mm thickness and an EAB_-10 (RL ≤ −10 dB) of 8.83 GHz, which demonstrated superior broadband and strong absorption performance. This work proposes a carbon hybridization strategy for structural modulation, providing novel insights for designing electromagnetic functional materials.