Size control of metal nanoparticle catalysts for the gas-phase synthesis of single-walled carbon nanotubes.
Nanoparticle catalysts are essential and indispensable for all syntheses of single-walled carbon nanotubes (SWCNTs). We have prepared size-controlled Co, Co-Mo, and Fe-Mo nanoparticles by the reversed micelle method as the catalysts for the gas-phase pyrolytic synthesis of SWCNTs. From the investigation of the relation between the sizes of the nanoparticles and the alkyl-chain lengths of the cationic surfactants, dialkyldimethylammonium bromides, it has been found that the alkyl groups of the surfactants could play a role in controlling the sizes of the nanoparticles and that the alkyl chain of the surfactant should be preferably less than 10 carbon atoms at most to prepare smaller-size nanoparticles with a narrow size distribution. The reduction of the particle size increases the number of nanoparticles in the colloidal solution and leads to a higher yield of SWCNTs.
Saito
Takeshi
T
Research Center for Advanced Carbon Materials, National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8565, Japan. takeshi-saito@aist.go.jp
Ohshima
Satoshi
S
Xu
Wei-Chun
WC
Ago
Hiroki
H
Yumura
Motoo
M
Iijima
Sumio
S