Chirality-selective synthesis of carbon nanotubes by catalytic-chemical vapor deposition using quasicrystal alloys as catalysts

We study ultrathin quasicrystal line (QC) films as catalysts for the synthesis of carbon nanotubes (CNTs). To optimize the conditions for the synthesis of CNTs with single chirality, it is important to understand the effects of the catalyst on the chirality-selectivity. Among QC alloys found so far, an icosahedral Al-Cu-Fe alloy system with fivefold symmetry was tested for a catalyst in the synthesis of CNTs by alcohol catalytic-chemical vapor deposition (CCVD). Cross-sectional scanning electron microscopic images of the samples revealed that vertically-aligned CNTs were synthesized reproducibly. It implies that QC films have a significant catalytic activity for the synthesis of CNTs. Moreover, preliminary results of chirality-selectivity are obtained by means of resonance Raman scattering. It is suggested that Al-Cu-Fe ultrathin films are useful for the preferential synthesis of armchair-type CNTs, that is, QC nanoclusters play an important role as catalyst in alcohol CCVD.