Synthesis of single-walled carbon nanotubes produced using a three layer Al/Fe/Mo metal catalyst and their field emission properties

• Published in: Carbon (New York) 2007-12, Vol.45 (15), p.3007-3014
• Main Authors: Chen, Y.S., Huang, J.H., Hu, J.L., Yang, C.C., Kang, W.P.
• Format: Article
• Language: English
• Subjects: Catalysis; Chemistry; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; General and physical chemistry; Materials science; Physics; Specific materials; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2007.09.042

Single-walled carbon nanotubes (SWCNTs) were synthesized on SiO 2/Si substrates by thermal chemical vapor deposition using an Al/Fe/Mo triple layer catalyst, methane (CH 4) as the carbon source, and a mixture of Ar/H 2 (10% H 2) as the carrier gas. The effects of volume ratio of CH 4 to Ar/H 2 (10% H 2), pretreatment time, growth temperature, and Al underlayer thickness on SWCNT growth were studied. The pretreatment time in Ar/H 2 and Al underlayer thickness were found to be crucial for a high-yield of high-purity SWCNTs, since they both governed the size of the catalyst nanoparticles. The optimum growth conditions were found to be a pretreatment time of 20 min, growth time of 10 min, growth temperature of 900 °C, and CH 4/Ar/H 2 flow rates of 50/900/100 sccm, with a catalyst composed of Al (2 nm)/Fe (1 nm)/Mo (0.5 nm). The SWCNTs grown under these conditions have excellent field emission characteristics with low turn-on and threshold fields of 2.4 and 4.3 V/μm, respectively, and a current density of 38.5 mA/cm 2 at 5 V/μm.