Functionalization of primary amine groups to single-walled carbon nanotubes by reacting fluorinated SWCNTs with ammonia gas at a low temperature

We functionalized primary amine groups (NH₂-) to single-walled carbon nanotubes (SWCNTs) by reacting fluorinated SWCNTs with ammonia gas at a low temperature and characterized NH₂-functionalized SWCNTs which were prepared by defluorinating the remaining fluorine groups via a hydrazine treatment. It is evident from the results of the Kaiser test and X-ray photoelectron spectroscopy that a few primary amine groups were functionalized onto the nanotubes. The average number of NH₂ groups in the NH₂-functionalized SWCNTs was 21.5 μmol/g. One primary amine group was functionalized per about 500 carbon atoms on the outermost surface of the bundled nanotube frame. The zeta potential of the SWCNTs was found to be +14 mV (pH = 3.0) and the specific capacitance of the NH₂-SWCNTs was approximately 1.7 times higher than the hc-SWCNTs at a scan rate of 10 mV/s, which indicated the functionalization effect of the primary amine groups.