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Title: How does acetonitrile modulate single-walled carbon nanotube diameter during CVD growth?

Abstract

There is a commercial demand for single-walled carbon nanotubes (SWCNTs) with uniform diameters and ( n, m) chiralities. Yet, controlling these structural parameters in practice remains a challenge. Recent studies have shown that acetonitrile reversibly modulates SWCNT diameter during chemical vapour deposition (CVD) growth. Here we propose a mechanism to explain this phenomenon using non-equilibrium quantum chemical molecular dynamics simulations. We reveal that acetonitrile-derived radicals actively abstract hydrogen from surface hydrocarbon species as the SWCNT nucleates. This forms hydrogen (iso)-cyanide as a principal chemical product, and decreases the overall surface carbon density during nucleation. By liberating hydrogen, the number of dangling bonds present at the interface of the nucleating carbon structure is increased, which in turn accelerates SWCNT nucleation kinetics. Critically, the number of pentagon rings formed in the SWCNT precursor cap structure increases. Because the nucleation kinetics are much faster than the kinetics of ring defect healing, the pentagons become ‘trapped’ in the growing SWCNT cap structure, and this leads to more highly-curved SWCNT caps. As a result, these more highly-curved caps, combined with the lower surface carbon density and the faster kinetics of nucleation and growth, will ultimately yield narrower-diameter SWCNTs in the presence of acetonitrile.

Authors:
 [1]; ORCiD logo [2]; ORCiD logo [1]
  1. Univ.of Newcastle, Callaghan, NSW (Australia)
  2. Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1502576
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Carbon
Additional Journal Information:
Journal Volume: 146; Journal Issue: C; Journal ID: ISSN 0008-6223
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Eveleens, Clothilde A., Irle, Stephan, and Page, Alister J.. How does acetonitrile modulate single-walled carbon nanotube diameter during CVD growth?. United States: N. p., 2019. Web. doi:10.1016/j.carbon.2019.02.027.
Eveleens, Clothilde A., Irle, Stephan, & Page, Alister J.. How does acetonitrile modulate single-walled carbon nanotube diameter during CVD growth?. United States. doi:10.1016/j.carbon.2019.02.027.
Eveleens, Clothilde A., Irle, Stephan, and Page, Alister J.. Wed . "How does acetonitrile modulate single-walled carbon nanotube diameter during CVD growth?". United States. doi:10.1016/j.carbon.2019.02.027.
@article{osti_1502576,
title = {How does acetonitrile modulate single-walled carbon nanotube diameter during CVD growth?},
author = {Eveleens, Clothilde A. and Irle, Stephan and Page, Alister J.},
abstractNote = {There is a commercial demand for single-walled carbon nanotubes (SWCNTs) with uniform diameters and (n, m) chiralities. Yet, controlling these structural parameters in practice remains a challenge. Recent studies have shown that acetonitrile reversibly modulates SWCNT diameter during chemical vapour deposition (CVD) growth. Here we propose a mechanism to explain this phenomenon using non-equilibrium quantum chemical molecular dynamics simulations. We reveal that acetonitrile-derived radicals actively abstract hydrogen from surface hydrocarbon species as the SWCNT nucleates. This forms hydrogen (iso)-cyanide as a principal chemical product, and decreases the overall surface carbon density during nucleation. By liberating hydrogen, the number of dangling bonds present at the interface of the nucleating carbon structure is increased, which in turn accelerates SWCNT nucleation kinetics. Critically, the number of pentagon rings formed in the SWCNT precursor cap structure increases. Because the nucleation kinetics are much faster than the kinetics of ring defect healing, the pentagons become ‘trapped’ in the growing SWCNT cap structure, and this leads to more highly-curved SWCNT caps. As a result, these more highly-curved caps, combined with the lower surface carbon density and the faster kinetics of nucleation and growth, will ultimately yield narrower-diameter SWCNTs in the presence of acetonitrile.},
doi = {10.1016/j.carbon.2019.02.027},
journal = {Carbon},
number = C,
volume = 146,
place = {United States},
year = {2019},
month = {2}
}

Journal Article:
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This content will become publicly available on February 13, 2020
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