Hierarchical Interfacial Engineering of SiO2@Graphite/Co Hybrids: Synergistic Dielectric-Magnetic Loss and Superior Microwave Absorption

Abstract

High-performance electromagnetic wave (EMW) absorbers are in critical demand to address the escalating electromagnetic pollution and interference issues resulting from the rapid advancement of modern electronic devices and wireless communication technologies. In this work, we report the synthesis of a series of SiO2@Gr/Co-X composite absorbers fabricated via a solution immersion–carbonization strategy. By precisely tuning the loading of magnetic Co nanoparticles, the electromagnetic parameters and microwave absorption properties of the composites were systematically tailored. It is found that SiO2@Gr/Co-20 exhibits strong absorption at 13.43 GHz, delivering a minimum reflection loss (RLmin) of −73.12 dB at a matching thickness of 1.52 mm and an effective absorption bandwidth (EAB) of 4.02 GHz at a matching thickness of 1.34 mm. Mechanistic analysis reveals that interfacial polarization, conductive loss, magnetic loss, and multiple scattering synergistically contribute to the superior EMW absorption performance. RCS simulations were also conducted to validate their practical application potential. This work not only offers a novel structural modulation strategy for the rational design of efficient EMW absorbers but also establishes a basis for the multifunctional integration of multicomponent heterogeneous composites.