Synthesis of carbon nanotubes by arc-discharge and chemical vapor deposition method with analysis of its morphology, dispersion and functionalization characteristics

In this paper, multi-walled carbon nanotubes are synthesized by arcdischarge and chemical vapor decomposition methods. Multi-walled carbon nanotubes are synthesized on thin film of nickel sputtered on silicon substrate by thermal chemical vapor deposition of acetylene at a temperature of 750 degrees C. The flow of current in arc-discharge method varies in the range 50-200 A. Further arc-synthesized carbon nanotubes are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and the results are compared with nanotubes grown by chemical vapor deposition method. XRD result shows a characteristic peak (0 0 2) at 26.54 degrees corresponding to the presence of carbon nanotubes. SEM and TEM results give morphology of as-synthesized multi-walled nanotubes. TEM results indicate synthesis of well-graphitized carbon nanotubes by arc-discharge method. Dispersion of arc-synthesized nanotubes in SDS solution under the effect of different sonication times is studied. Dispersion of nanotubes in SDS solution is analyzed using UV-vis-NIR spectroscopy and it shows an absorption peak at 260 nm. It was found that with the increase in sonication time, the absorption peak in UV-vis-NIR spectra will increase and optimum sonication time was 2 hours. Functionalization of synthesized carbon nanotubes by H2SO4 and HNO3 acids has been studied and analysis of functionalized groups has been done using FT-IR spectroscopy and compared and the results are reported in this paper. FT-IR spectroscopy verifies the presence of carboxylic groups attached to carbon nanotubes. These functional groups may change properties of carbon nanotubes and may be used in vast applications of carbon nanotubes.