The influence of different atmosphere gases on the growth and structure of double-walled carbon nanotubes

To clarify the impact of different atmosphere gases on the growth and structure of double-walled carbon nanotubes (DWCNT), we used a graphite rod containing some catalyst as our anode and prepared DWCNTs with the arc-discharge method in an atmosphere of pure Ar, pure H2, and a mixture (1: 1 by volume) of Ar and H2 at different pressures, respectively. The Fe family metal-sulfide composite (FeS, NiS, CoS) used as the catalyst was mixed with high-purity graphite powder in a certain proportion and was then enclosed into a drilled hole in the anode. By altering the discharge conditions and examining the product of the DWCNT using high-resolution electron microscopy, we found the optimum growth condition to be the atmosphere of mixed (1: 1) Ar and H2, and the ratio (FeS: NiS: CoS: C = 1: 1: 1: 15 wt %) for the catalyst of the Fe family metal-sulfide composite.