Ultralight N-doped platanus acerifolia biomass carbon microtubes/RGO composite aerogel with enhanced mechanical properties and high-performance microwave absorption

Biomass-derived carbon material, an ideal lightweight and sustainable electromagnetic wave (EMW) absorption material, has adjustable dielectric properties, which is one of its greatest advantages. However, how to comprehensively control its composite dielectric constant to achieve strong microwave absorption (MA), wide effective absorption bandwidth (EAB), light mass, and thin thickness is still challenging. In this study, the N-doped biomass carbon microtubes/RGO composite aerogel (N-BCMT/RGO) with a three-dimensional multistage pore network structure was prepared by using the waste Platanus acerifolia tree fruit-derived biomass microtubes as the base, through heteroatom doping and composite conductive material. Among them, the doping of nitrogen atoms introduces numerous defects and promotes the formation of a heterogeneous interface, which plays an important role in regulating conduction and polarization loss. Secondly, the introduction of conductive material effectively promotes the hopping and migration of electrons, which further enhances the conduction loss. Moreover, the close binding of BCMT and RGO causes N-BCMT/RGO aerogel to exhibit enhanced mechanical properties. The special multistage hole structure allows N-BCMT/RGO to exhibit good impedance matching and ultra-low density (0.0121 g/cm3), which also exhibits an ultra-wide EAB of 8.36 GHz and a minimum reflection loss (RLmin) of −55.45 dB at an ultra-low filler loading of 2 wt%. This opens up an avenue for the realization of novel microwave absorbers with light weight and high performance, and the proposed comprehensive control strategy for the composite permittivity of biomass-carbon materials provides new ideas for activating the MA behavior of metal-free carbon-based absorbers.