Dual Resonance Behavior and Enhanced Microwave Absorption Performance of Fe₃O₄@C@MoS₂ Composites with Shape Magnetic Anisotropy

Abstract

Ternary hierarchical Fe₃O₄@C@MoS₂ composites and binary hierarchical Fe₃O₄@C composites were successfully fabricated by a modified mixed solvothermal method, a self-oxidation polymerization method, and a hydrothermal process. Their magnetic properties and microwave absorption performance were investigated. Dual resonance behavior was observed in the Fe₃O₄@C@MoS₂ composites. One of the resonances was attributed to natural resonance with a resonance frequency of 2.58 GHz, which was much higher than that for Fe₃O₄ bulk (1.5 GHz). The other originated from the superparamagnetic/ferromagnetic relaxation with a resonance frequency of 12.45 GHz. The minimum reflection loss (RL_min) reached -64.30 dB with a matched thickness of 2.24 mm at 11.64 GHz, and the maximum effective absorption bandwidth (EAB_max) covered 6.39 GHz with a matched thickness of 1.89 mm. In addition, the maximum Radar cross section (RCS) reduction value reached 31.90 dB m² at a scattering angle of 0°. Electron holography analysis confirmed a dense magnetic absorption network in the Fe₃O₄@C@MoS₂ composites. The boost in microwave absorption performance was caused by the synergistic effects of magnetic and dielectric properties owing to the ternary hierarchical structure, shape magnetic anisotropy, and incorporation of 1T/2H MoS₂. Besides, the binary hierarchical Fe₃O₄@C composites also exhibited good absorbing performance caused by natural resonance, with an RL_min of -52.90 dB at 5.80 mm, an EAB_max of 5.98 GHz at 3.38 mm, and a relatively high RCS reduction value of 13.04 dB m² at θ = 20°. This work paves the way for designing multicomponent hierarchical absorbers with broadband and intensive microwave absorption.