Nitrogen-doped porous biomass-derived carbons for enhanced hydrophobicity, microwave absorption and thermal insulation

Porous heteroatom–doped carbon architectures have emerged as advanced multifunctional microwave absorbers. This study fabricates nitrogen–doped biomass-derived carbon using jackfruit through a coordinated KOH/urea activation–carbonization methodology. The carbonization temperature effectively regulates the porous structure, resulting in the formation of a thin material with a low density and broadband absorption. Upon being incorporated into a paraffin matrix at a 10 wt% loading (J-800 sample), the material exhibits enhanced electromagnetic (EM) wave absorption capabilities: a minimum reflection loss (RL_min) of − 46.3 dB at 1.75 mm, and an effective absorption bandwidth (EAB) of 5.6 GHz (covering the entire Ku band) at a thickness of 1.8 mm. This performance extends to the C-band range, where the material maintains an RL_min of −28.9 dB and the EAB delivers 3.8 GHz (4.2−8.0 GHz) coverage across a thickness range of 2.85–5 mm. This nitrogen-doped biomass-derived carbon simultaneously achieves multifunctional superiority, exhibiting an 18.15 dB m² radar cross-section reduction, 131.7° hydrophobic surface characteristics, and efficient thermal management properties − stabilizing at 50.5 °C within 15 min under a thermal exposure of 157.5 °C. Concurrent infrared stealth compatibility complements these attributes, confirming that the developed strategy offers a streamlined synthetic route for engineering integrated microwave absorbers with combined EM attenuation, environmental resilience, and multispectral concealment capabilities.