Effect of the State of Catalytic Nanoparticles on the Growth of Vertically Aligned Carbon Nanotubes.

In this study, vertically aligned carbon nanotubes (VA-CNTs) were grown from filler-added LB films with accumulated AlFe2O4 nanoparticles and palmitic acid (C16) as the filler molecule after differ-ent hydrogen reduction temperatures of 500 & DEG;C and 750 & DEG;C, and the grown VA-CNTs were compared and evaluated. As a result, VA-CNTs were ap-proximately doubled in length after 500 & DEG;C hydrogen reduction compared to 750 & DEG;C hydrogen reduction when AlFe2O4 NPs were used. On the other hand, when the catalyst area ratio was decreased by using palmitic acid, i.e., the distance between CNTs was increased, VA-CNTs rapidly short-ened after 500 & DEG;C hydrogen reduction, and VA-CNTs were no longer ob-tained even in the range where VA-CNTs were obtained in 750 & DEG;C hydro-gen reduction. The inner and outer diameters of VA-CNTs decreased with decreasing catalyst area ratio at 750 & DEG;C hydrogen reduction and tended to increase at 500 & DEG;C hydrogen reduction. The morphology of the catalyst nanoparticles after CVD was observed to change significantly depending on the hydrogen reduction temperature and catalyst area ratio. These ob-servations indicate that the state of the catalyst nanoparticles immediately before the CNT growth process greatly affects the physical properties of the CNTs.