Hierarchical carbon/Fe3O4 composites derived from wood with efficient multiband microwave absorption

Hierarchical carbon/Fe3O4 composites were successfully fabricated using wood as a sustainable carbon precursor via in situ magnetic nanoparticle loading and subsequent carbonization. Benefiting from the intrinsic porous cellular architecture of wood and the homogeneous anchoring of Fe3O4 nanoparticles, the resulting composites exhibit a synergistic combination of conductive loss, magnetic loss, and interfacial polarization. Systematic electromagnetic characterization reveals that the optimized composite delivers a minimum reflection loss of −59.21 dB at a thin matching thickness, along with a broad effective absorption bandwidth covering multiple frequency regions. The enhanced microwave absorption performance is primarily attributed to the improved impedance matching induced by hierarchical porosity, multiscale interfaces, and the balanced dielectric-magnetic loss mechanisms. This work demonstrates a feasible strategy for converting renewable biomass into high-performance, lightweight, and broadband microwave absorbers, highlighting significant potential for electromagnetic interference shielding and stealth applications.