Hierarchical carbon/Fe3O4 composites from bamboo for high-performance microwave attenuation

Hierarchical carbon/Fe 3 O 4 composites based on bamboo were successfully prepared through an integrated process consisting of lignin removal, high-pressure impregnation of Fe 3 O 4 precursors, and subsequent carbonization at various temperatures. During pyrolysis, the delignified bamboo template retained its inherent porous architecture, which supplied numerous transport channels and interfacial sites for the immobilization of magnetic nanoparticles. Structural analyses verified that Fe 3 O 4 nanoparticles were homogeneously embedded throughout the carbon framework, generating stable magnetic-carbon hybrid architectures. The carbonization temperature played a decisive role in regulating the internal morphology, magnetic behavior, and electromagnetic parameters of the resulting materials. Among the series, the BBC-1000 sample demonstrated the most outstanding microwave absorption capability, delivering a minimum reflection loss of -68.51 dB at a matching thickness of 2.5 mm and an effective absorption bandwidth of 3.42 GHz when the thickness was 1.6 mm. The improved attenuation capability results from the synergistic interplay of dielectric and magnetic loss processes, facilitated by the hierarchical porous architecture, numerous heterogeneous interfaces, and evenly distributed magnetic nanoparticles. In addition, radar cross-section simulations further confirm the superior electromagnetic suppression capability of coatings derived from BBC-1000. These findings provide an eco-friendly strategy for the development of lightweight, tunable, and high-performance biomass-based microwave absorbing materials (MAMs), with significant potential for applications in electromagnetic interference mitigation and stealth technologies.