Abstract
H-2 is considered an indispensable component of the atmosphere for the growth of high-quality single-wall carbon nanotubes (SWCNTs) by chemical vapor deposition. However, details of the roles H-2 playing are still unclear due to the complex conditions of SWCNT growth. In this study, we elucidate the functions of H-2 in the selective growth of semiconducting SWCNTs (s-SWCNTs) by using monodispersed uniform Fe nanoparticles as a catalyst. High-quality s-SWCNTs were synthesized by finely tuning the concentration of H-2 and the other growth parameters. Experimental data combined with atomistic simulations indicate that H-2 not only adjusts the concentration of the carbon source, but also serves as a mild etchant that selectively removes small carbon caps grown by a perpendicular mode from the Fe nanoparticles. These results provide useful hints for the controlled growth of SWCNTs with a semiconducting or metallic conductivity, and even a specific chirality. (C) 2020 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.