Study on the Preparation of Core–Shell Carbon-Based Absorbing Materials with a Small Particle Size of Fe₃O₄

In this investigation, we successfully synthesized a core–shell nanomaterial featuring ternary Fe3O4@mSiO2@Carbon nanoparticles by utilizing mesoporous silica as the interlayer to disperse small particles of Fe3O4, which served as the core of the particles. The ternary nanoparticles Fe3O4@mSiO2@Carbon have demonstrated impressive electromagnetic wave (EW) absorption characteristics, with the most outstanding particle obtained by adding 0.2 g of resorcinol, achieving a minimum reflection loss (RLmin) value of −72.06 dB at an absorber thickness of 4.3 mm. In addition, it has the widest effective absorption bandwidth (EAB), reaching 6.21 GHz at a thickness of 2.7 mm. The radar cross section (RCS) reduction of the composite has been verified by CST simulation in the far field, and the strongest RCS reduction value was up to 38.06 dBm2 with a scattering angle of 33°. Our findings indicate that the addition of the mesoporous silica layer benefits the uniform dispersion of the magnetic small particles of Fe3O4, improves the impedance matching of the material, and enhances the absorption ability of EW. We posit that our synthesis process can serve as a valuable reference for the development of high-performance, lightweight, and low-density carbon-based EW absorbing nanomaterials.