▎ 摘　　要

In this work, ultralight nitrogen-doped reduced graphene oxide/multi-walled carbon nanotubes (NRGO/MWCNTs) composite aerogels were fabricated via a facile hydrothermal and lyophilization two-step strategy. Results of morphology analysis showed that the as-synthesized binary composite aerogels displayed unique three-dimensional porous netlike structure with a pore size around dozens of microns, which was composed of the partial stack of neighboring porous RGO flakes attached by some tiny MWCNTs. Moreover, the effects of complexing with MWCNTs, lengths of MWCNTs and filler contents on the electromagnetic wave (EMW) absorption properties of obtained composite aerogels were investigated. Significantly, the as-prepared NRGO/MWCNTs composite aerogel with long MWCNTs exhibited notably enhanced EMW absorption capacity than that of binary composite aerogel with short MWCNTs and single NRGO aerogel. Specifically, the composite aerogel with long MWCNTs and doped nitrogen content of 7.07 wt% (bulk density similar to 7.2 mg cm(-3)) presented the optimal reflection loss of -53.3 dB at 6.5 GHz (C band) and broad absorption bandwidth of 5.2 GHz (from 11.1 to 16.3 GHz) under a small matching thickness of merely 2.0 mm and low filler content of 15 wt%. Interestingly, the reflection loss values were all less than -20 dB with matching thicknesses changing from 1.5 to 4.5 mm. Furthermore, the relationship between reflection loss and filler contents was revealed. Additionally, the underlying EMW absorption mechanisms were clarified. Therefore, the as-fabricated NRGO/MWCNTs composite aerogels could be promising candidates as light-weight and high-performance EMW absorbers.