Synthesis of polyaniline-coated carbon nanotubes and study on their pH-sensitive conductivity.

We report the synthesis of polyaniline-coated-carbon nanotubes (PANI-c-CNTs) composites by using water-soluble CNTs with phenyl sulfonate groups as templates. A series of characterizations including transmission electron microscopy (TEM), Fourier-Transform Infrared Spectroscopy (FTIR) and UV-vis spectroscopy were conducted to investigate the formation of PANI coating on the surfaces of the CNTs. The thickness of PANI coating in the PANI-c-CNTs composites was controlled by adjusting concentrations of aniline and CNTs. The conductivities of PANI-c-CNTs composites were measured by using conductive atomic force microscopy (c-AFM). It was found that the conductivities of PANI-c-CNTs composites were remarkably affected after doping and dedoping process of PANI coating by different pH solution. Therefore, our preliminary result indicates that as-prepared PANI-c-CNTs composites may be used as gas sensor such as HCl and NH3 vapor.