Conductive Ag Microspheres with Lychee-like Morphology on the Enhanced Microwave Absorption Properties of MWCNTs

The conductive Ag microspheres were designed and prepared by the method of electroless plating via depositing Ag nanoparticles on polystyrene (PS) microspheres. The three-dimensional (3D) absorber hybrids of Ag@MWCNTs were fabricated by the combination of conductive Ag microspheres and multiwalled carbon nanotubes (MWCNTs). The morphology and structure of the absorbents were analyzed and characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, which demonstrated that the Ag@MWCNT hybrids presented a 3D network structure, and the morphology of Ag microspheres was lychee-like. The influence of lychee-like Ag microspheres on the microwave absorption performance of MWCNTs was characterized by a vector network analyzer. The maximum reflection loss (RL) of Ag@MWCNTs was -39.09 dB at 8.10 GHz, of which the bandwidth of RL < -10 dB was 2.00 GHz (7.10-9.10 GHz). In contrast, the PS@MWCNT hybrids had a maximum RL of -22.34 dB at 9.30 GHz. These results indicated that the conductive Ag microspheres with lychee-like morphology were significant to improve the absorption properties of MWCNTs because of the increased conducting pathways and multiple reflection scattering interfaces.