Fe3C/Fe implanted hierarchical porous carbon foams for lightweight and broadband microwave absorption

Porous carbon materials typically exhibit excellent microwave absorption performance and lightweight characteristics, providing a positive significance for controlling the composites weight. This work employed a onestep method, and in situ growth techniques to fabricate a foam-structure Fe3C/Fe/C with a density of only 0.142 g/cm3. The carbon skeleton encapsulates Fe3C/Fe nanoparticles to slow down its oxidation in the natural environment. Remarkably, the Fe3C/Fe/C composite achieves an impressive effective bandwidth of 5.73 GHz with a 2.2 mm thickness and only 10 wt% filling ratio. The outstanding performance can be ascribed to the enhanced interfacial polarization caused by high porosity. Additional nitrogen doping provides active sites to enhance dipole polarization. Additionally, after in-depth analysis of the various magnetic loss mechanisms present in Fe3C/Fe/C, we have revealed the promotion of introducing magnetic nanoparticles on the microwave absorption performance of foam-like carbon. This work provides an effective reference for reducing the weight of microwave absorbers, simplifying preparation methods, and understanding the mechanisms of magnetic nanoparticles in foam-like carbon.