Mechanism of the initial stages of nitrogen-doped single-walled carbon nanotube growth |
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Authors: | Susi Toma Lanzani Giorgio Nasibulin Albert G Ayala Paola Jiang Tao Bligaard Thomas Laasonen Kari Kauppinen Esko I |
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Affiliation: | Department of Applied Physics, Aalto University School of Science, Aalto, Espoo, Finland. toma.susi@tkk.fi |
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Abstract: | We have studied the mechanism of the initial stages of nitrogen-doped single-walled carbon nanotube growth illustrated for the case of a floating catalyst chemical vapor deposition system, which uses carbon monoxide (CO) and ammonia (NH(3)) as precursors and iron as a catalyst. We performed first-principles electronic-structure calculations, fully incorporating the effects of spin polarization and magnetic moments, to investigate the bonding and chemistry of CO, NH(3), and their fragments on a model Fe(55) icosahedral cluster. A possible dissociation path for NH(3) to atomic nitrogen and hydrogen was identified, with a reaction barrier consistent with an experimentally determined value we measured by tandem infrared and mass spectrometry. Both C-C and C-N bond formation reactions were found to be barrierless and exothermic, while a parasitic reaction of HCN formation had a barrier of over 1 eV. |
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