Study on the Preparation\nof Core–Shell Carbon-Based\nAbsorbing Materials with a Small Particle Size of Fe<sub>3</sub>O<sub>4</sub>

In\nthis investigation, we successfully synthesized a core–shell\nnanomaterial featuring ternary Fe<sub>3</sub>O<sub>4</sub>@mSiO<sub>2</sub>@Carbon nanoparticles by utilizing mesoporous silica as the\ninterlayer to disperse small particles of Fe<sub>3</sub>O<sub>4</sub>, which served as the core of the particles. The ternary nanoparticles\nFe<sub>3</sub>O<sub>4</sub>@mSiO<sub>2</sub>@Carbon have demonstrated\nimpressive electromagnetic wave (EW) absorption characteristics, with\nthe most outstanding particle obtained by adding 0.2 g of resorcinol,\nachieving a minimum reflection loss (RLmin) value of −72.06\ndB at an absorber thickness of 4.3 mm. In addition, it has the widest\neffective absorption bandwidth (EAB), reaching 6.21 GHz at a thickness\nof 2.7 mm. The radar cross section (RCS) reduction of the composite\nhas been verified by CST simulation in the far field, and the strongest\nRCS reduction value was up to 38.06 dBm<sup>2</sup> with a scattering\nangle of 33°. Our findings indicate that the addition of the\nmesoporous silica layer benefits the uniform dispersion of the magnetic\nsmall particles of Fe<sub>3</sub>O<sub>4</sub>, improves the impedance\nmatching of the material, and enhances the absorption ability of EW.\nWe posit that our synthesis process can serve as a valuable reference\nfor the development of high-performance, lightweight, and low-density\ncarbon-based EW absorbing nanomaterials.