Imaging as-grown single-walled carbon nanotubes originated from isolated catalytic nanoparticles

Multifunctional Catalysts for Singlewall Carbon Nanotube Synthesis

“…Although the detailed structure is unknown, it has been shown experimentally that the inactive nanoparticles remain isolated during nanotube growth. 42 It is thus reasonable to rule out the aggregation of those nanoparticles as the cause for such inactivity.…”

“…First, many kinds of mono-MNPs have been found at the end of SWNTs synthesized in slow-growing environments, including CVD and a specially designed, two-step laser vaporization process. 42,54 Second, under otherwise identical conditions, the yield of SWNTs is generally much higher when two metals instead of one are used. 42 If the two metals stay apart from each other in individual nanoparticles or catalytic entities, the observed enhancement phenomena in those experiments would be difficult to explain.…”

“…42,54 Second, under otherwise identical conditions, the yield of SWNTs is generally much higher when two metals instead of one are used. 42 If the two metals stay apart from each other in individual nanoparticles or catalytic entities, the observed enhancement phenomena in those experiments would be difficult to explain. Thus, the two metals must stay in close vicinity, most likely next to each other, to enable the enhancement.…”

“…Si substrates and the CVD method were used for nanotube synthesis. 42 Their results clearly indicated that SWNTs can be grown from these isolated Fe nanoparticles. However, some of the morphologically identical nanoparticles failed to initiate the growth of SWNTs.…”

“…On the other hand, nanotube synthesis using these nanoparticles is similar to those in gas phase if these nanoparticles are lifted off from the substrate by nanotubes. 42 In their experiments, Fe nanoparticles made from ferritin proteins were used as catalysts. Si substrates and the CVD method were used for nanotube synthesis.…”