Synthesis of ultralight three-dimensional nitrogen-doped reduced graphene oxide/multi-walled carbon nanotubes/zinc ferrite composite aerogel for highly efficient electromagnetic wave absorption.

Developing light-weight, thin thickness and high-efficiency electromagnetic wave (EMW) absorbers was regarded as an effective strategy for dealing with the increasingly serious problem of electromagnetic radiation pollution. Herein, nitrogen-doped reduced graphene oxide/multi-walled carbon nanotubes/zinc ferrite (NRGO/MWCNTs/ZnFeO) composite aerogel was synthesized via solvothermal followed by hydrothermal and lyophilization processes. Morphological characterization results manifested that the attained ternary composite aerogel displayed unique three-dimensional porous netlike structure, which was composed of partial stack of adjacent NRGO sheets entangled by MWCNTs and decorated with ZnFeO microspheres. Moreover, the influences of complexing with conductive MWCNTs and magnetic ZnFeO, and filler contents on the EMW attenuation performance of ternary composite aerogel were examined. Significantly, the ternary composite aerogel exhibited notably strengthened EMW absorption capacity in comparison with NRGO/MWCNTs composite aerogel, NRGO aerogel and ZnFeO microspheres. The minimum reflection loss (RL) was up to -52.6 dB at a thin matching thickness of 1.7 mm and effective absorption bandwidth (EAB) was 5.1 GHz (12.7-17.8 GHz) under an ultrathin thickness of 1.65 mm with a low filler content of 10 wt%. Remarkably, the |SRL| (|specific RL value per thickness|) could achieve 30.9 dB/mm, which overwhelmed almost all the reported RGO-based composite aerogels. Besides, the possible EMW absorption mechanisms of as-synthesized ternary composite aerogel were proposed. It was believed that our results provided a valuable guidance for fabricating graphene-based composites with three-dimensional netlike structure as light-weight, thin thickness and high-performance EMW absorbers.