Reed root-derived hierarchical porous carbon via one-step activation-carbonization for high-performance...

Biomass-derived porous carbon materials have been widely investigated owing to their great potential in microwave absorption, but their limited pore structures have, to some extent, hindered further improvements in performance. In this work, hierarchical porous carbon (RRC) absorbers were successfully fabricated from renewable reed roots, featuring naturally oriented microchannels, via a facile one-step KOH activation-carbonization strategy. The influence of activator dosage on the microstructural evolution and electromagnetic response was systematically investigated. The results demonstrate that the optimized RRC-3 sample possesses a unique honeycomb-like hierarchical architecture with a high specific surface area (742.8 m² g^-1) and abundant lattice defects. Owing to the synergistic interplay between optimized impedance matching and enhanced dielectric loss (comprising interfacial polarization, dipolar polarization, and conductive loss), RRC-3 achieves a remarkable minimum reflection loss (RL_min) of -66.2 dB at a thin matching thickness of 1.74 mm. Furthermore, a broad effective absorption bandwidth (EAB) of 5.6 GHz is realized at 2.5 mm, spanning across the high-frequency X band and part of the Ku band. Finite-element simulations (SCD, VLD, and RCS) further validate the exceptional incident-field coupling and volumetric dissipation capabilities, with a predicted radar cross-section (RCS) reduction of approximately 44 dB. This study provides a sustainable and effective paradigm for converting agricultural waste into high-performance, green microwave functional materials.