Growth of single-walled carbon nanotubes by the rapid heating of a supported catalyst

Single-walled carbon nanotubes (SWNTs) have been synthesized by the rapid injection of a nickel formate/silica gel catalyst/support into a hot fluidized-bed reactor. The initial rapid heating of the catalyst in the hydrocarbon feedstock was found to be essential for the nucleation of SWNTs since only amorphous or graphitic carbon particles were formed without it. These results suggest that the rapid heating of the catalyst precursor enables the formation of the small metal particles required for SWNT growth, probably due to the accelerated thermal decomposition of the catalyst precursor and enhanced nucleation rate. The growth of the SWNTs was investigated by the adoption of different methods for introducing the catalyst, and by varying the synthesis parameters including the catalyst loading, hydrocarbon gas flow rate, and concentration. The results found that SWNTs formed only under certain reaction conditions. The nanotubes produced were characterized by electron microscopy and Raman spectroscopy.