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arXiv · 1312.7143

Structure and stability of hydrogenated carbon atom vacancies in graphene

M. Casartelli·S. Casolo·G. F. Tantardini·R. Martinazzo
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Abstract

Adsorption of hydrogen atoms to a carbon atom vacancy in graphene is investigated by means of periodic \emph{first principles} calculations, up to the fully hydrogenated state where six H atoms chemically bind to the vacancy. Addition of a single H atom is highly exothermic and barrierless, and binding energies remain substantial for further hydrogenation, with a preference towards structures with the least number of geminal pairs. Thermodynamic analysis shows that defective graphene is extremely sensitive to hydrogenation, with the triply hydrogenated anti- structure prevailing at room temperature and for a wide range of H$_{2}$ partial pressures, from $\sim1$ bar down to $<10^{-20}$ bar. This structure has one unpaired electron and provides a spin-half local magnetic moment contribution to graphene paramagnetism. Comparison of our results with recent TEM, STM and $μ$-SR experiments suggest that carbon atom vacancies may actually be hydrogenated to various degrees under varying conditions.

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M. Casartelli, S. Casolo, G. F. Tantardini, R. Martinazzo. 2013-12-26. Structure and stability of hydrogenated carbon atom vacancies in graphene. https://arxiv.org/abs/1312.7143

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