Sodium chloride assisted synthesis of porous magnetic carbon nanocomposites containing cobalt nanoparticles for high-performance electromagnetic wave-absorption

High-performance electromagnetic wave-absorbing materials have attracted much attention owing to their wide application in military stealth, camouflage, and electromagnetic protection. Carbon materials have more advantages in achieving the performance goals of thin, light, wide, and strong absorption. The combination of ferromagnetic components is commonly used to further improve the absorption ability of carbon materials. Herein, porous Co/C nanocomposites attached with different Co content were prepared through the sodium chloride assisted carbonization process of glucose precursor containing cobalt salts. Dipole polarizations and dielectric relaxation in the carbon matrix, as well as interfacial polarizations at the heterogeneous interfaces collectively contributed to the total dielectric loss. Meanwhile, the existence of Co nanoparticles effectively improved the magnetic properties and increased magnetic loss. In addition, the impedance matching performance was also improved. As a result, the prepared Co/C nanocomposites achieved an absorption bandwidth of nearly 6 GHz, covering almost the whole Ku band from 12.1 to 18.0 GHz. And the minimum reflection loss exceeded −60 dB. This work provided a simpler and more effective approach to prepare high-performance absorbing materials.