High-crystallinity single-walled carbon nanotube aerogel growth: Understanding the real-time catalytic decomposition reaction through floating catalyst chemical vapor deposition

Abstract

In this study, high-purity single-walled carbon nanotubes (SWCNTs) are synthesized with additional carrier gas through floating catalyst chemical vapor deposition. The presence of Ar during the SWCNT aerogel formation affects to the precursor decomposition and to the formation of different reactive hydrocarbons. Furthermore, the concentration of produced various carbon species is sensitive to the carrier gas compositions. The in-situ sampling methods prove the thermodynamic pathway for the hydrocarbon cracking during carbon nanotube (CNT) aerogel formation process. The addition of Ar promoted the formation of reactive hydrocarbon species, such as CH3, CH4, and C2H4/CO, to improve CNT morphology and graphitization. Ar has improved purity of CNTs compared to when only H2 is used. The synthesized CNTs were narrow in size, and the diameter decreased from 1.8 to 1.2 nm with the carrier gas composition (Rx) according to Ar addition. The IG/ID ratio of the CNTs changed from 78 to 3 at R0.1 and R0.57, respectively. Furthermore, the purity also increased to approximately 10% from 78% to 91% depending on Rx.