Core-Shell Ni@Onion-Like Carbon Nanocapsules-Decorated Reduced Graphene Oxides with Enhanced Microwave Absorption Properties in GHz Range

Ni@onion-like carbon (OLC)/reduced graphene oxide (RGO) nanocomposites were synthesized, and their multicomponent microstructure was confirmed by X-ray diffraction, transmission electron microscopy, Raman spectra, the thermal gravimetric analysis and magnetic hysteresis loops. The obtained nanocomposite possesses a unique structure, in which core-shell Ni@OLC nanocapsules are decorated on the surface of RGOs. The synergistic erect of the dielectric loss of RGO and OLC and the magnetic loss of Ni nanoparticles can be constructed. The RGO can provide tremendous electric dipoles. Multi-interface among RGO, OLC and Ni nanoparticles can enhance dielectric performance and cause multiple reflections. The combination of these merits makes the nanocomposite a promising candidate material for electromagnetic absorber. The 20 wt.% nanocomposite-paraffin composite can possess an optimal reflection loss (RL) of -47: 5 dB at 9.75 GHz with a thickness of 3.1 mm. When the thickness is 2.0 mm, the RL of composite can reach -32: 6 dB at 17.4 GHz. The effective frequency is 6.54 GHz (11.16-17.7 GHz) for 2.4 mm thickness layer.