Ordered cellular 2D/2D biomass-derived carbon nanosheet/MXene aerogels for ultralight and high-performance microwave absorption

Three-dimension (3D) porous aerogel has been regarded as a lightweight and effective electromagnetic (EM) absorber, but the rational design of component and ordered macroscopic structure with low cost is still a big challenge. In this work, we constructed an ultralight biomass-derived carbon nanosheets/MXene (CNMX) composite aerogel with ordered porous connected network by an ice template method. The two-dimension (2D) hybrid nanosheets is parallelly arranged with constant spacing and interconnected by tentacle bridge to forming 3D oriented porous cellular structure. Further, the interlamellar spacing can be effectively tuned by regulating the content of carbon nanosheets (CN). Optimized 3D oriented network effectively extends EM wave transmission paths and improves impedance matching. When the thickness is 2.5 mm, CNMX3 achieves strong reflection loss (RL) intensity of -48.5 dB and broad effective absorption bandwidth (EAB) of 5.2 GHz under filling ratio of only 7 wt%. Moreover, CNMX4 reaches a broad EAB of 5.8 GHz at only thickness of 2.1 mm. CST simulation is also performed to reveal the microwave absorption mechanism and demonstrate the potential application of the aerogel in EM stealth technology.