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Larsson, J. Andreas
Publications (2 of 2) Show all publications
Silvearv, F., Larsson, P., Jones, S. L. L., Ahuja, R. & Larsson, J. A. (2015). Establishing the most favorable metal-carbon bond strength for carbon nanotube catalysts. Journal of Materials Chemistry C, 3(14), 3422-3427
Open this publication in new window or tab >>Establishing the most favorable metal-carbon bond strength for carbon nanotube catalysts
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2015 (English)In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 3, no 14, p. 3422-3427Article in journal (Refereed) Published
Abstract [en]

We have studied a wide range of transition metals to find potential carbon nanotube (CNT) catalysts for chemical vapor deposition (CVD) production. The adhesion strengths between a CNT and a metal cluster were calculated using first principle density functional theory (DFT) for all 1st, 2nd and 3rd row transition metals. We have developed the criterion that the metal-carbon adhesion strength per bond must fulfill a Goldilocks principle for catalyzing CNT growth and used it to identify, besides the well known catalysts Fe, Co and Ni, a number of other potential catalysts, namely Y, Zr, Rh, Pd, La, Ce and Pt. Our results are consistent with previous experiments performed either in a carbon arc discharge environment or by a CVD-process with regard to CNT catalyst activity.

National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-252053 (URN)10.1039/c5tc00143a (DOI)000351871600025 ()
Available from: 2015-04-29 Created: 2015-04-28 Last updated: 2017-12-04Bibliographically approved
Li, Y., Ahuja, R. & Larsson, J. A. (2014). Communication: Origin of the difference between carbon nanotube armchair and zigzag ends. Journal of Chemical Physics, 140(9), 091102
Open this publication in new window or tab >>Communication: Origin of the difference between carbon nanotube armchair and zigzag ends
2014 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 140, no 9, p. 091102-Article in journal (Refereed) Published
Abstract [en]

In this work, we have found that the difference between armchair and zigzag ends of carbon nanotubes (CNTs) does not pertain at close study for individual bonds and thus alternative strategies need to be developed to reach the ultimate goals in selective growth. Based on first-principles simulations, the difference between binding strengths for CNTs of different chirality was investigated using hydrogen dissociation energies at their passivated ends. When all H atoms are removed collectively we find the well-known difference: that armchair bonds are much weaker than zigzag ones, which is typically seen for both CNT ends and graphene edges. However, when individual H atoms are removed we find almost no difference in hydrogen dissociation energies, small difference in bond lengths, which by association means small difference in C-C and M-C binding energies. We show convincingly that the difference in binding energy between armchair and zigzag ends is due to a fragment stabilization effect that is only manifested when all (or several neighbouring) bonds are broken. This is because at armchair ends/edges neighbouring dangling bonds can pair-up to form C C triple bonds that constitute a considerable stabilization effect compared to the isolated dangling bonds at zigzag ends/edges. Consequently, in many processes, e. g., catalytic growth where bonds are normally created/broken sequentially, not collectively, the difference between armchair and zigzag ends/edges cannot be used to discriminate growth of one type over the other to achieve chiral selective growth. Strategies are discussed to realize chirality selective growth in the light of the results presented, including addition of C-2-fragments to favor armchair tubes. (C) 2014 AIP Publishing LLC.

National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-224470 (URN)10.1063/1.4867744 (DOI)000334067400003 ()
Available from: 2014-05-15 Created: 2014-05-13 Last updated: 2017-12-05Bibliographically approved
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