Excellent Microwave Absorption Properties of Fe 4 N Reinforced Honeycomb Porous Carbon

ABSTRACT 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/Fe 4 N triphasic composites (Fe/Fe 4 N/PC) via facile freeze‐drying and nitridation procedures. Specifically, the nitridation process under an NH 3 atmosphere facilitates the in situ formation of Fe 4 N magnetic nanoparticles through the reaction between Fe and N species. The synergistic integration of the honeycomb porous structure, Fe/Fe 4 N magnetic particles, and biomass‐derived carbon enriches the electromagnetic loss mechanisms, encompassing conduction loss, dipole polarization, magnetic loss, and multiple reflections. Consequently, the Fe/Fe 4 N/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/Fe 4 N/PC composite prominently reduces the RCS signal by 42.6 dB·m 2 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.