One-step sintering construction of electromagnetic synergistic Co₇Fe₃/Co@CBC nanocomposites for enhanced microwave...

Based on the synergistic modulation of electromagnetic parameters and microstructure design, multidimensional porous magnetic carbon-based nanocomposites have become ideal materials with efficient absorption properties. What's more, a carbon-magnetic alloy composite is a commonly used and efficient microwave absorber. In this paper, Co₇Fe₃/Co@CBC (CFCC) nanocomposites with strong magnetism, a three-phase composition, and a three-dimensional porous structure were synthesized by reducing Fe²⁺ and Co²⁺ using chestnut-shell biomass carbon (CBC). Biomass carbon with a higher specific surface area provides numerous active sites for Co₇Fe₃ nanosheets and Co nanospheres to form three-dimensional ping-pong chrysanthemum-like nanocomposites, which generate rich heterogeneous interfaces and conductive network structures. By adjusting the amount of added biomass, the electromagnetic parameters can be effectively regulated to achieve efficient microwave absorption properties. When the amount of biomass added varies within the range of 1.0 to 2.5 g, all samples exhibit a favorable effective absorption bandwidth (EAB) of over 5.88 GHz. In particular, the CFCC-2.0 composite exhibits optimal microwave absorption properties, with a minimum reflection loss (RL_min) value of -59.25 dB and an EAB of 6.34 GHz at a thickness of 2.8 mm. The simulation and modeling analysis results of radar cross section (RCS) further confirm the exceptional attenuation capability of composite materials at multiple incident angles. The exceptional microwave absorption properties and stability of EAB for the Co₇Fe₃/Co@CBC nanocomposite make it a promising candidate in the field of absorbing materials. This work also provides some feasible ideas for designing stable broadband wave-absorbing materials.