Enhanced microwave absorbing properties of PVP@multi-walled carbon nanotubes/graphene three-dimensional hybrids

An absorber hybrid was fabricated by the incorporation of PVP treated multi-walled carbon nanotubes (PVP@MWNTs) and graphene nanoplatelets (GNPs) using an ultrasonication filtration method. The microwave absorbing properties of PVP@MWNTs/GNPs hybrids were investigated in the frequency range of 8.2-12.4 GHz. The structure and morphology of the PVP@MWNTs/GNPs hybrids was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy. The SEM and TEM results showed that GNPs were covered by PVP@MWNTs; the embedding of PVP@MWNTs into GNPs layers endows PVP@MWNTs/GNPs hybrids with optimum dispersion, which is helpful to the significant improvement in electron transfer effectiveness. The PVP@MWNTs/GNPs hybrids reveal excellent microwave absorbing properties. The maximum reflection loss value (RL) of PVP@MWNTs/GNPs is -26.5 dB at 11.29 GHz with a thickness of 2 mm, and the effective absorption (<-10 dB) bandwidth reaches 1.6 GHz. However, the RL of pristine MWNTs is about -5 dB at 12 GHz, and GNPs is -4.43 dB at 12.23 GHz. The results indicate that the combination of PVP@MWNTs and GNPs have a synergetic effect on the improved microwave absorbing properties.