Carbon nanotube: the inside story

Area of Science:

• Materials Science
• Nanotechnology
• Chemistry

Background:

• Carbon nanotubes (CNTs) are highly sought-after materials in nanotechnology research.
• Their discovery as a byproduct of fullerenes via direct current (DC) arc discharge marked a significant advancement.
• Research has explored various CNT production methods, with a focus on arc discharge techniques.

Purpose of the Study:

• To review the history and discovery of CNTs.
• To focus on CNTs produced by arc discharge in a hydrogen atmosphere.
• To describe methods for producing multi-walled (MWCNTs), single-walled (SWCNTs), and double-walled carbon nanotubes (DWCNTs).

Main Methods:

• Direct current (DC) arc discharge of pure graphite rods in a hydrogen atmosphere to produce MWCNTs.
• Arc evaporation of graphite rods with metal catalysts for SWCNT production.
• Development of Arc Plasma Jet (APJ) and Ferrum-Hydrogen (FH) arc methods for SWCNTs.
• Review of purification methods for as-produced SWCNTs.

Main Results:

• DC arc discharge in hydrogen yields highly crystalline MWCNTs with narrow inner diameters.
• Raman spectra of these MWCNTs show a high-intensity G-band, a unique radial breathing mode at 570 cm⁻¹, and a new peak near 1850 cm⁻¹.
• Carbon nanowires (CNWs) with linear carbon chains within MWCNTs were observed.
• Arc evaporation with catalysts produced SWCNTs as macroscopic webs.
• APJ and FH arc methods were developed for SWCNT synthesis.

Conclusions:

• Arc discharge in hydrogen is an effective method for producing high-quality MWCNTs.
• Specific arc discharge techniques enable the synthesis of SWCNTs and DWCNTs.
• Ongoing research focuses on optimizing production and purification methods for various carbon nanotube structures.