A flexible chemical vapor deposition method to synthesize copper@carbon core–shell structured nanowires and the study of their structural electrical properties

Abstract

Copper@carbon nanowires (NWs) or nanorods (NRs) with outer diameters between 30 and 90 nm and lengths ranging from 700 nm up to 10 μm have been prepared with high yield via a chemical vapor deposition (CVD) method followed by thermal decomposition of copper(II)-acetylacetonate. The morphology and microstructure of the Cu@C NWs/NRs were characterized by scanning electron microscopy (SEM) and tunneling electron microscopy (TEM), which suggest that these as-grown copper cores with graphite carbon encapsulated inside showed one tip closed and another tip open-ended. The X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX) analysis data indicate that the Cu@C NWs/NRs are free of any contamination, while the electron diffraction (ED) analysis revealed the NWs/NRs to be single crystals. Raman spectra of the deposits obtained with increasing reaction temperature show the transformation tendency from graphite carbon to amorphous carbon. The nanowire/rod growth mechanism has also been discussed. Moreover, Cu@C NWs/NRs are transformed into empty carbon nanotubes with Cu nanoparticles attached to the end after a thermal treatment above 800 °C. This conversion process is of great importance for reuse and recycling of nanomaterials. In addition, electronic transport properties of single nanowire have also been discussed.