Soybean meal-derived heteroatom self-doped hierarchical porous carbon for efficient microwave absorption

The complexity and high cost of preparing high-performance wave-absorbing materials have limited their large-scale production.In this study, N self-doped soybean meal porous carbon(SPC) materials with multilevel pore structures were synthesized from protein-rich waste soybean meal via simple pretreatment, KOH-activation, and high-temperature carbonization.Thanks to balanced impedance matching and conductive losses, as well as the advantages provided by multiple losses from dipole polarization and interfacial polarization induced by nitrogen-containing groups, the prepared material exhibits a minimum reflection loss (RL_min) of −40.97 dB at 9.12 GHz with a low filler loading of 10 wt%, and an effective absorption bandwidth (EAB) of 3.32 GHz at a thickness of 2.80 mm. Simulations of radar cross-section (RCS) demonstrated that SPC outperformed the ideal electrical conductor in minimizing RCS at a scattering angle of 0°, with a notable reduction of 19.01 dB m².This work offers a cost-effective approach for converting biomass waste into efficient porous microwave absorbers.