Excellent Microwave Absorption Properties of Fe₄N Reinforced Honeycomb Porous Carbon

Biomass-derived carbon-based composites, renowned for their extensive sources, low cost, low density, and unique pore structure, have garnered increasing attention as electromagnetic wave (EMW) absorbers. In this work, tangerine peel featuring a natural honeycomb porous structure was selected as the precursor to construct honeycomb porous carbon/Fe/Fe₄N triphasic composites (Fe/Fe₄N/PC) via facile freeze-drying and nitridation procedures. Specifically, the nitridation process under an NH₃ atmosphere facilitates the in situ formation of Fe₄N magnetic nanoparticles through the reaction between Fe and N species. The synergistic integration of the honeycomb porous structure, Fe/Fe₄N magnetic particles, and biomass-derived carbon enriches the electromagnetic loss mechanisms, encompassing conduction loss, dipole polarization, magnetic loss, and multiple reflections. Consequently, the Fe/Fe₄N/PC composites exhibit exceptional EMW absorption performance: the minimum reflection loss (RL_{m i n}) reaches -55.93 dB at a thickness of 2.6 mm, and the maximum effective absorption bandwidth (EAB) achieves 5.41 GHz at 1.7 mm. Additionally, radar cross section (RCS) simulation results demonstrate that the Fe/Fe₄N/PC composite prominently reduces the RCS signal by 42.6 dB·m² at 16°, confirming its superior practical stealth potential. This study provides insightful guidance for the design and eco-friendly fabrication of honeycomb porous structured absorbers, offering a strategy for developing high-performance and sustainable EMW absorbers.