SiC whiskers-reduced graphene oxide composites decorated with MnO nanoparticles for tunable microwave absorption

An excellent electromagnetic (EM) wave absorber with lightweight, broad bandwidth and high-efficiency absorption is urgently demanded for solving the EM interference pollution. A MnO nanoparticles@SiC whiskers/reduced graphene oxide (MnONPs@SiCw/RGO) hybrid composite with enhanced EM wave absorption performance was successfully synthesized by a hydrothermal strategy followed with thermal treatment. The results demonstrate that the annealing temperature was critical for the morphology of MnONPs, resulting in different impedance matching and attenuation constant. Correspondingly, the MnONPs@SiCw/RGO hybrid composite obtained at 800 degrees C presented the best EM wave absorption property, whose minimum reflection loss (RLmin) reached - 54.04 dB at 17.9 GHz with ultrathin matching thickness of only 1.59 nm and the effective absorption bandwidth (EAB) could be dramatically broadened to 7.4 GHz, covering the entire Ku-band. Additionally, almost full-band absorption with a qualified bandwidth of 14.2 GHz could be achieved by changing the sample thickness from 1.5 to 5.0 mm. The enhancement results should be mainly attributed to the synergistic and complementary effects of the conduction loss and polarization relaxation loss. Our work exhibits that the hierarchical MnONPs@SiCw/RGO hybrid composites might as a promising candidate for high-efficiency microwave absorbers, and provides an effective way for constructing microwave absorber in the future.