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Nitrogen segregation in nanocarbons

Lookup NU author(s): Professor Patrick Briddon

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Abstract

We explore the behaviour of nitrogen doping in carbon nanomaterials, notably graphene, nanotubes, and carbon thin films. This is initially Via a brief review of the literature, followed by a series of atomistic density functional calculations. We show that at low concentrations, substitutional nitrogen doping in the sp(2)-C graphenic basal plane is favoured, however once the nitrogen concentration reaches a critical threshold there is a transition towards the formation of the more thermodynamically-favoured nitrogen terminated 'zigzag' type edges. These can occur either via formation of finite patches (polycyclic aromatic azacarbons), strips of sp(2) carbon with zigzag nitrogen edges, or internal nitrogen-terminated hole edges within graphenic planes. This transition to edge formation is especially favoured when the nitrogen can be partially functionalised with, e.g. hydrogen. By comparison with available literature results, notably from electron energy loss spectroscopy and X-ray spectroscopy, the current results suggest that much of the nitrogen believed to be incorporated into carbon nanoobjects is instead likely to be present terminating the edges of carbonaceous impurities attached to nanoobject's surface. By comparison to nitrogen-doped tetrahedrally amorphous carbon, we suggest that this transition at around 10-20% nitrogen concentration and above towards sp(2) coordination via internal nitrogen-terminated edge formation may be a general property of nitrogen-doped carbon materials.

Publication metadata

Author(s): Ewels CP, Erbahar D, Wagner P, Rocquefelte X, Arenal R, Pochet P, Rayson M, Scardamaglia M, Bittencourt C, Briddon P

Publication type: Article

Publication status: Published

Journal: Faraday Discussions

Year: 2014

Volume: 173

Pages: 215-232

Print publication date: 01/12/2014

Online publication date: 13/06/2014

Acceptance date: 13/06/2014

ISSN (print): 1359-6640

ISSN (electronic): 1364-5498

Publisher: Royal Society of Chemistry

URL: http://dx.doi.org/10.1039/c4fd00111g

DOI: 10.1039/c4fd00111g

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