Synthesis of zinc oxide particles coated multiwalled carbon nanotubes: Dielectric properties, electromagnetic interference shielding and microwave absorption

Zinc oxide (ZnO) nanoparticles were coated on the surfaces of multiwalled carbon nanotubes (MWCNTs). High resolution transmission electron microscopy images show that the wurtzite ZnO immobilized on the MWCNTs is single-crystalline with a preferential [0 0 0 2] growth direction. A capacitor was generated by the interface of ZnO and MWCNTs, and a resistor–capacitor model could well describe the relationships between the structure and the dielectric properties, electromagnetic interference shielding and microwave-absorption of the composites in the frequency range of 2–18 GHz. The network built by ZnO-immobilized MWCNTs could contribute to the improvement of electrical properties. Resonant peaks associated with the capacitor formed by the interface were observed in the microwave absorption spectra, which suggest that reflection–loss peaks greatly broadens the absorption bandwidth.

Graphical abstractA resistor–capacitor model could well describe the relationships between the structure and the dielectric properties, electromagnetic interference shielding and microwave-absorption of the composites in the frequency range of 2–18 GHz. The resonant behavior associated with the multiwalled carbon nanotubes/zinc oxide (MWCNTs/ZnO) interface greatly broadens the absorption band.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► ZnO-immobilized on multiwalled carbon nanotubes (MWCNTs/ZnO) have resonant behavior. ► A resistor–capacitor model describes the relation between the structure and properties. ► The composite with 40 wt% MWCNTs/ZnO has good electromagnetic interference shielding. ► Two different types of absorption peaks are found in the MWCNTs/ZnO composites. ► The existence of MWCNTs/ZnO interface broadens the absorption band.