Graphene has been regarded as one of the most promising two-dimensional nanomaterials. Even so, graphene was still faced with several key issues such as impedance mismatching and narrow bandwidth, which have hindered the practical applications of graphene-based nanocomposites in the field of microwave absorption materials. Herein, a series of Si-modified rGO@Fe₃O₄ composites were investigated and fabricated by a simple method. On one hand, the degree of defects in graphene carbon could be tuned by different silane coupling reagents, which were beneficial to enhancing the dielectric loss. On the other hand, the spherical Fe₃O₄ nanoparticles provided the magnetic loss resonance, which contributed to controlling the impedance matching. Subsequently, the electromagnetic absorption (EMA) properties of Si-modified rGO@Fe₃O₄ composites with poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) were investigated in this work. As a result, the Si(2)-rGO@Fe₃O₄/PVDF-co-HFP composite exhibited the excellent EMA performance in the range of 2-18 GHz. The maximum reflection loss (RL_max) reached -32.1 dB at 3.68 GHz at the thickness of 7 mm and the effective absorption frequency bandwidth for reflection loss (RL) below -10 dB was 4.8 GHz at the thickness of 2 mm. Furthermore, the enhanced absorption mechanism revealed that the high-efficiency absorption performance of Si(2)-rGO@Fe₃O₄/PVDF-co-HFP composite was attributed to the interference absorption (quarter-wave matching model) and the synergistic effects between Si(2)-rGO@Fe₃O₄ and PVDF-co-HFP. This work provides a potential strategy for the fabrication of the high-performance EMA materials.

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