Herein, cerium oxide nanoparticles decorated multi-walled carbon nanotubes (MWCNTs) nanocomposites were successfully synthesized by a facile one-step hydrothermal route. The structure, compositions, micromorphology and electromagnetic parameters of the obtained nanocomposites were carefully characterized. Results revealed that the well-designed three-dimensional (3D) conductive networks and rich oxygen vacancy defects were formed in situ in the as-prepared nanocomposites, which were beneficial to the electromagnetic wave (EMW) absorption. Remarkably, the binary nanocomposite with the additive amount of MWCNTs of 45 mg exhibited the minimum reflection loss (RLmin) of
51.1 dB and effective absorption bandwidth (EAB, RL less than
10 dB) of 3.4 GHz (7.8e11.2 GHz) with a thin thickness of 2.6 mm. Furthermore, the EAB could reach 14.16 GHz (88.5% of 2e18 GHz) by facilely adjusting the coating thicknesses from 1.5 to 5 mm, which spanned the whole C, X and Ku bands. Besides, the influence of the additive amounts of MWCNTs on the EMW absorption performance was investigated and the possible EMW absorption mechanism was proposed. It was believed that this work could shed light on the designing novel MWCNTs-based nanocomposites as the high-efficiency EMW absorbers.