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

Synthesis of a forest of double/triple walled CNTs of uniform diameters by plasma enhanced CVD using monodisperse iron oxide nanoparticles

“…It was shown previously that iron oxide particles were not active enough to produce VA-CNTs and that the catalyst activity was improved by adding a small amount of vanadium to the iron oxide particles. 12 In the present case, on the contrary, the catalyst activity of nanoparticles was high enough to grow VA-CNTs. We suppose that a change of iron oxide particles into metallic ones was encouraged by the use of plasma (see the ESI † for XPS analysis of catalytic nanoparticles before and after the application of plasma and the raise in the temperature) and as a result, the activity of the nanoparticles was enhanced.…”

“…Various groups have tried to synthesise CNTs of uniform diameters using liquid phase catalyst nanoparticles. [2][3][4][11][12][13] The liquid phase method is a realistic approach to the control of the diameter and density of nanoparticles, which has two major advantages, that is, (a) its scalability to production of a large quantity of nanoparticles while maintaining a narrow size distribution; and (b) its ability to form a dense self-assembled monolayer. However, the low catalyst activity and agglomeration of nanoparticles become crucial problems at elevated temperature.…”

“…However, there are two drawbacks: (a) some additional steps are necessary for the deposition of dendrimers on a silicon substrate; and (b) a pre-heat treatment of nanoparticles is necessary for increasing the catalyst activity, as a result of which the internal diameter of CNTs varies significantly. I. Gunjishima et al 12 synthesised VA-DWCNTs using Fe-V-O nanoparticles instead of Fe-O ones due to the low activity of iron oxide particles.…”

Nanotubes

“…22 Dense vertically aligned MWCNTs containing only a few walls have been grown from Fe-V-O nanoparticles by CVD. 23 Decomposition of methane over MgO impregnated with various precious metals such as Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, or Pt afford MWCNTs (with the graphite layers parallel to the tube axis) with Group 8 and 9 metals and carbon nanofibers (CNFs) with herringbone type graphene sheets with Group 10 metals. 24 Semiconductor nanoparticles of SiC, Ge, and Si produce SWCNTs and DWCNTs in CVD with ethanol.…”

Carbon Nanotubes from Unconventional Resources: Part A: Entangled Multi-Walled Carbon Nanotubes and Part B: Vertically-Aligned Carbon Nanotubes

“…The most commonly used active catalyst for growing CNTs are magnetic elements such as Fe, Co or Ni. Gunjishima et al [46] used Fe-V bimetallic catalyst for synthesize of aligned DWCNTs. Recently, there have been appreciable attempt of using ferrocence as a catalyst for synthesis of aligned carbon nanotubes [47].…”