Formation of Carbon Species on Ni(111):  Structure and Stability

The structures and stabilities of a set of carbon species on the Ni(111) surface, as well as the energy barriers of the initial stages of carbon growth, were computed by using density functional theory. It was found that the stability is on the order of graphitic monolayer > C in Ni bulk > car...

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Published in:Journal of physical chemistry. C 2007-07, Vol.111 (29), p.10894-10903
Main Authors: Wang, Sheng-Guang, Liao, Xiao-Yuan, Cao, Dong-Bo, Li, Yong-Wang, Wang, Jianguo, Jiao, Haijun
Format: Article
Language:English
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Summary:The structures and stabilities of a set of carbon species on the Ni(111) surface, as well as the energy barriers of the initial stages of carbon growth, were computed by using density functional theory. It was found that the stability is on the order of graphitic monolayer > C in Ni bulk > carbon chain > small cluster > atomic carbon. The formation of adsorbed graphitic monolayer is most preferred on Ni(111) thermodynamically. The adsorbed carbon atoms exist at the coverage of 0.25 and 0.5 monolayer, and they reconstruct Ni(111) at the coverage of 0.75 and 1 monolayer. The reconstruction will be interesting for self-assembly of surface structures and needs experimental confirmation. The adsorbed C2 and C3 carbon clusters on Ni(111) have linear structures, in which the terminal carbons prefer occupying 3-fold hollow sites. In the stable adsorbed C3 cluster, the middle carbon atom occupies a top site. The linear C4 cluster and the branched C4 cluster have very similar stability. Like the adsorbed graphitic monolayer, the branched C4 cluster occupies similar surface sites, and this implies a simple carbon growth mechanism. On the basis of the computed energy barriers, the lateral transfer and clustering of carbon is favored kinetically, while the carbon atoms sinking into the Ni bulk have high energy barriers. During the adsorption processes, electrons transfer from the Ni surfaces to the adsorbed carbon species, while the spin densities of the adsorbed carbon species and the Ni surfaces decrease.
ISSN:1932-7447
1932-7455
DOI:10.1021/jp070608v