Preparation and study of the electrical, magnetic and thermal properties of Fe3O4 coated carbon nanotubes

In this work, functionalized multiwalled carbon nanotubes (f-MWCNTs) were coated with Fe3O4 nanoparticles using a straightforward wet chemical method. The obtained magnetic nanocomposites were characterized by using Fourier transform infrared (FTIR) and X-ray diffraction (XRD) spectroscopies to investigate the chemical bonds and structures. Transmission electron microscopy (TEM) revealed the microstructure of the iron oxide coated MWCNTs. The electrical resistivity of pristine, functionalized, and MWCNT/Fe3O4 nanocomposites were measured by the two-probe method. The results showed that the electrical resistivity of the carbon nanotubes was decreased by the chemical functionalization and decoration with Fe3O4 nanoparticles. It was also observed that with increasing the applied voltage the resistivity of all the samples increased. Magnetic characterization showed a superparamagnetic behavior for the synthesized MWCNT/Fe3O4 nanocomposites. Thermal conductivity measurements of the samples in water showed that the functionalization of nanotubes decreased the thermal conductivity of water, but decorating the carbon nanotubes by magnetic nanoparticles increased the thermal conductivity of water.