Incorporation of CoO@Co yolk-shell nanoparticles and ZnO nanoparticles with graphene sheets as lightweight and high-performance electromagnetic wave absorbing material

A facile and efficient strategy is developed to incorporate yolk-shell CoO@Co nanoparticles (NPs) and ZnO NPs with graphene sheets. The diameter and the space between CoO shell and Co yolk are merely 12.0 nm and 1.0 nm, respectively, while the diameter of ZnO NPs is in the range of 4.0-10.0 nm. Due to the small size of NPs and the special structural feature, the resultant graphene-based composite exhibits excellent electromagnetic wave (EMW) absorption properties. Typically, the minimal reflection loss (R-L) value reaches to -51.1 dB at 11.3 GHz at the absorber thickness of 2.6 mm, and less than -20 dB at the absorber thickness ranging from 2.0 to 5.0 mm. Moreover, the absorption bandwidths corresponding to the RL values below -10 dB (90% of EMW wave energy consumption) is up to 4.7 GHz (from 9.5 to 14.2 GHz) at a thickness of 2.6 mm. Furthermore, the addition amount of the composite into paraffin matrix is merely 20 wt%, less than that of most EMW absorber reported previously. Therefore, such novel hybrid materials can be used as a kind of candidate for lightweight EMW absorbing material. (C) 2017 Elsevier B.V. All rights reserved.