Rational Design of CoFe@C@SiO2 Dual-Core-Shell Composites with Synergistic Magnetic-Dielectric Loss for Enhanced Broadband Microwave Absorption

Electromagnetic radiation not only threatens biological health but also causes electromagnetic compatibility issues in electronic devices and poses formidable challenges to stealth technology in military applications. Herein, a CoFe@C@SiO2 composite absorber is reported. CoFe@C materials were fabricated through a synergistic strategy combining efficient microwave hydrothermal treatment and subsequent reduction under an inert atmosphere, after which SiO2 was in situ polymerized onto the surface of the CoFe@C composites. When the amount of tetraethyl orthosilicate (TEOS) was 2.5 mL and the absorber thickness was 2.5 mm, the material achieved a minimum reflection loss (RLmin) of −61.34 dB and an effective absorption bandwidth (EAB) of 6.76 GHz. Radar cross-section (RCS) simulation results further confirm the excellent microwave absorption performance of the prepared sample and its great potential for practical applications. Owing to its unique dielectric properties and its ability to form heterogeneous interfaces with carbon-based and metallic components, SiO2 effectively enhances the microwave absorption performance of these composites. This work provides an effective and sustainable strategy for utilizing SiO2 to develop high-performance microwave-absorbing materials.