title: Effect of rare-earth component of the RE/Ni catalyst on the formation and nanostructure of single-walled carbon nanotubes.
abstract: A systematic experimental study has been carried out on the efficiency of bimetallic catalysts based on Ni and the rare-earth elements Y, La, Ce, Nd, Gd, Tb, Dy, Ho, Er, and Lu (group A) and Eu, Sm, Yb, and Tm (group B) in the synthesis of single-walled carbon nanotubes (SWNTs). The two groups give quite different results when analyzed by a combination of SEM/TEM and Raman and UV-NIR spectroscopies. The elements in group A have an obvious catalytic effect and increase the yield of SWNTs dramatically, whereas those in group B are not efficient catalysts. The diameter distribution of the synthesized SWNTs was also affected by the rare-earth element used. For group A metals, there is a tendency that the fraction of small-diameter tubes decreases with decreasing ionic radius of the rare-earth element used. EDX and X-ray analyses indicate that group A metals deposit on the cathode deposits and form rare-earth carbides, whereas no group B metals are found in cathode deposits, except for a small amount of Tm present in the form of thulium carbide. Further analysis indicates that there is a very strong correlation between the ability to form rare-earth carbides and the catalytic efficiency for the formation of SWNTs.
authors.affiliation: National Lab of Superhard Materials, Jilin University, Changchun 130012, China.
authors.forename: Mingguang
authors.initials: M
authors.lastname: Yao
authors.forename: Bingbing
authors.initials: B
authors.lastname: Liu
authors.forename: Yonggang
authors.initials: Y
authors.lastname: Zou
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
authors.forename: Tian
authors.initials: T
authors.lastname: Cui
authors.forename: Guangtian
authors.initials: G
authors.lastname: Zou
authors.forename: Jixue
authors.initials: J
authors.lastname: Li
authors.forename: B
authors.initials: B
authors.lastname: Sundqvist