Synthesis of Fe3O4@SiO2@C/Ni microspheres for enhanced electromagnetic wave absorption

•The absorbing material with a bilayer core-shell structure of Fe3O4@SiO2@C/Ni was prepared.•Magnetic nanoparticles are introduced to enhance magnetic loss.•The minimum reflection loss and maximum effective bandwidth were −39.8 dB and 10.1 GHz.•The synergistic effect of dielectric loss and magnetic loss of composite materials. With the rapid development of electromagnetic and radar technology, military stealth technology has become an essential measure of a country's military strength. In this paper, hydrothermal and improved Stober methods prepared the composite absorbing material Fe3O4@SiO2@C/Ni with a double core-shell structure. The minimum reflection loss of the sample is −38.9 dB, and the maximum effective bandwidth is 10.1 GHz. By changing the thickness of the carbon layer and the thickness of the SiO2 layer, the absorption performance of the prepared sample can be adjusted to achieve the best impedance matching. The synergistic effect of the composite's dielectric loss and magnetic loss improves its microwave absorption capacity, making it a promising choice for absorptive material applications. [Display omitted]