▎ 摘　　要

In this work, trimanganese tetroxide nanoparticles decorated nitrogen-doped reduced graphene oxide (NRGO/Mn3O4) composite aerogels were synthesized via a hydrothermal route and subsequent lyophilization treatment. The obtained composite aerogels possessed low bulk density (12.5-14.1 mg.cm(-3)) and particular three-dimensional (3D) porous netlike structure formed through stacking of neighboring NRGO flakes. Moreover, the microwave attenuation properties of as-synthesized composite aerogels could be modulated by regulating the contents of Mn3O4 and matching thicknesses. Significantly, the attained composite aerogel with the content of Mn3O4 of 20.2 wt% presented the integrated excellent electromagnetic attenuation performance, i.e. the optimal minimum reflection loss achieved -52.9 dB (larger than 99.999% absorption) at a thin matching thickness of 1.6 mm and broadest effective absorption bandwidth was as high as 5.4 GHz (from 12.3 GHz to 17.7 GHz, covering 90% of Ku-band) under a very thin thickness of only 1.5 mm. Additionally, the potential microwave dissipation mechanisms of as-fabricated composite aemgels were illuminated, which primarily originated from the optimized impedance matching, strengthened interfacial polarization and dipole polarization loss, and notable conduction loss. Our results would shed light on the development of lightweight and high-performance graphene-based 3D microwave absorption composites.