▎ 摘　　要

Three-dimensional (3D) graphene-based structures have attracted much attention due to their unique physicochemical properties and potential applications in various fields. In this work, we develop a facile strategy for growing Co and Zn-contained nitrogen-doped carbon nanotubes on the graphene sheets for the absorption of electromagnetic wave (EMW). The as-fabricated 3D structures with a larger surface area have high electrical conductivities, abundant defects, numerous interfaces and porous feature, endowing them to excellent EMW absorption performance. The minimal reflection loss and efficient absorption bandwidth of the optimized 3D structure can reach to -47.31 dB and 4.01 GHz at a low thickness of merely 1.5 mm, respectively. Even at the thickness of 1.2-1.5 mm, the minimal reflection losses are less than -10 dB. Furthermore, the filler mass loading of the 3D structures is only 6 wt%, lower than those of most of the reported absorbers. Our results highlight the importance of 3D structures composed of graphene and nitrogen-doped carbon nanotubes to high-efficiency EMW absorption. (C) 2019 Elsevier Ltd. All rights reserved.