P-doped cellulose nanofiber derived carbon aerogel with efficient thermal insulation and electromagnetic wave absorption performances

Developing eco-friendly electromagnetic wave (EMW) absorption materials with simultaneous compression-resistant resilience, thermal insulation properties, and stability in complex environments is a formidable challenge. Inspired by the honeycomb structures, we utilized the concepts of directional freezing and carbonization to fabricated versatile P-doped hydrophilic carbon aerogel (CPA) for more demanding and complex applications. The numerous boundary-type defects generated by graphene nanosheets (GNs) and multi-walled carbon nanotubes (MWCNTs) on the surfaces of the honeycomb structure served as polarization centers, resulting in an effective absorption bandwidth (EAB) spanning from the C band to the Ku band (4–18 GHz, 1.0–4.0 mm) yielding a minimum reflection loss (RL, −72.02 dB) for CPA-800. The radar cross section (RCS) values of CPA-800 were below −15 dBm² within the range of −90° < θ < 90°, possessing a strong radar wave attenuation capability for potential application in both air and underwater conditions. The thermal insulation performance of CPA-800 reduced the sample temperature from 300 °C to 63 °C, and possessed outstanding structural stability during prolonged and intense flame exposure. This work represents a novel multifunctional platform for EMW absorption, thermal insulation, and resilience materials in various harsh environments.