Scalable Growth of Single-Walled Carbon Nanotubes with Highly Uniform Structure
Here, a scalable floating catalyst chemical vapor deposition (FCCVD) method is developed for the production of single-walled carbon nanotubes (SWCNTs) with controlled structure. For the first time, water is used as the growth promoter in the FCCVD process to modulate the growth of SWCNTs. At an optimum water concentration of ca 115 ppm, water assisted FCCVD process synthesizes SWCNTs having an extremely narrow chirality distribution. In particular, the proportion of (9,8) and (8,7) semiconducting tubes was dramatically enhanced to 45% with 27% of the (9, 8) tube in the end product. This is attributed to the changes in both SWCNT diameter and chiral angle. The experiment results and accurate quantum chemical molecular dynamics simulations show that the addition of water affects the nucleation and size distribution of nanoparticle catalysts, thus resulting in the growth of SWCNTs with highly uniform structure. This direct and continuous water-assisted FCCVD provides the possibility for the mass production of high-quality SWCNTs with controlled structure.