Preferential Growth of Single-Walled Carbon Nanotubes with Metallic Conductivity
Avetik R. Harutyunyan,1,*
Gugang Chen,1
Tereza M. Paronyan,2
Elena M. Pigos,1
Oleg A. Kuznetsov,1
Kapila Hewaparakrama,2
Seung Min Kim,3,4
Dmitri Zakharov,4
Eric A. Stach,3,4
Gamini U. Sumanasekera2
Single-walled carbon nanotubes can be classified as either
metallic or semiconducting, depending on their
conductivity, which is
determined by their chirality. Existing synthesis methods cannot
controllably grow
nanotubes with a specific type
of conductivity.
By varying the noble gas ambient during thermal annealing
of the catalyst, and in combination
with oxidative and reductive
species, we altered the fraction
of tubes
with metallic conductivity from one-third
of the population to a maximum
of 91%. In situ
transmission electron microscopy studies reveal that this variation
leads to differences in both morphology and coarsening behavior
of the nanoparticles that we used to nucleate
nanotubes. These
catalyst rearrangements demonstrate that there are correlations
between catalyst morphology and resulting nanotube electronic
structure and indicate that chiral-selective
growth may be possible.
1 Honda Research Institute USA, 1381 Kinnear Road, Columbus, OH 43212, USA.
2 Department of Physics and Astronomy, University of Louisville, Louisville, KY 40292, USA.
3 School of Materials Engineering, Purdue University, 701 Northwestern Avenue, West Lafayette, IN 47907, USA.
4 Birck Nanotechnology Center, Purdue University, 1205 West State Street, West Lafayette, IN 47907, USA.
* To whom correspondence should be addressed. E-mail: aharutyunyan{at}honda-ri.com
