Synthesis of vertically aligned, double-walled carbon nanotubes from highly active Fe–V–O nanoparticles Original Research Article

Monodispersed Fe–V–O nanoparticles were prepared by a liquid-phase synthesis to be used as catalysts for carbon nanotube (CNT) growth. Vertically aligned, dense CNTs have been grown from the highly active Fe–V–O nanoparticles by chemical vapor deposition. Diameter distribution of CNTs (3.7 ± 0.6 nm) was consistent with that of the original nanoparticles (3.1 ± 0.5 nm), and the value was smaller than those of other reported vertically aligned CNTs from as-prepared nanoparticles. TEM study showed that the CNTs consisted mainly of double-walled CNTs (single: 14%, double: 74%, and triple: 12%). The CNT diameter increased to 4.4 ± 0.8 nm as the growth temperature was increased from 810 to 870 °C. Energy dispersive X-ray spectroscopy of nanoparticles before and after the CNT growth revealed that the V content decreased from 7.2 to 2.7 at.%, suggesting that the segregation of Fe and V played an important role for the high activity of the Fe–V–O nanoparticles.