Ultra-lightweight carbon nanocomposites as microwave absorber with high absorbing performance derived from flour

Carbon materials, known for their lightweight properties, are widely utilized in electromagnetic wave absorption applications. In order to overcome the limitations of effective absorption of electromagnetic waves by a single carbon material, magnetic cobalt nanoparticles were incorporated into a carbon network derived from flour, resulting in the development of Co/C nanocomposites with a porous structure through fermentation. The results show that the electromagnetic wave absorbing material prepared in this way has advantages such as thin thickness (1.80 mm), lightweight, wide effective bandwidth (8.07 GHz), and high absorption capacity (− 61.6 dB). The absorption capability of the material originates from the multi-level interfaces in Co/C nanocomposites, the porous carbon structure formed during flour fermentation, and the dielectric relaxation generated during the polarization process. The excellent absorption performance is mainly attributed to the optimization of impedance matching and attenuation factor. The presence of amorphous carbon in the carbon network reduces the condensation and oxidation of magnetic cobalt nanoparticles, thus enhancing the impedance matching. By adjusting the Co/C ratio inside the nanocomposites, the impedance matching of the Co/C nanocomposites is improved, and the absorption capacity of the Co/C nanocomposites is improved. This study reports a simple method of preparing the porous microwave absorbing nanocomposites by carbonizing flour-based precursors and finally optimizing their absorption capacity by adding metal nanoparticles.