Significant decrease of electrical resistivity by carbon nanotube networks in copper-MWCNTs nanocomposites: a detailed microstructure study

Abstract CNTs-reinforced composites are promising candidates for various applications due to their enhanced electrical and mechanical properties. In this work, copper/multiwall-carbon-nanotube composites with various weight fractions (1, 2, and 5 wt.%) of MWCNTs were synthesized chemically by the dissociation of copper nitrate- containing MWCNTs followed by reduction under hydrogen atmosphere. Bulk composite pellets were prepared by precompaction under uniaxial pressure and isostatic pressure followed by sintering under hydrogen/argon atmosphere. Raman spectroscopy results show a continuous increase in CNTs defects throughout the synthesis, compaction and sintering processes. Transmission electron microscopy (TEM) revealed good dispersion, proper adhesion of copper nanoparticles onto the CNTs and CNTs network formation. X-ray diffraction and electron energy loss spectroscopy confirmed the full reduction of copper oxide into metallic copper. The Cu-MWCNTs composites exhibited a decrease in electrical resistivity when the CNTs volume fraction increased. The composite containing 5 wt.% MWCNTs exhibited a significant resistivity decrease of two orders of magnitude at room temperature.