Very recently, two dimensional sheets of sp2-bonded carbon atoms, called graphene, have been the subject of numerous experimental as well as theoretical investigations. The most of those studies are motivated by the potential application of graphene in several nanodevices [1]. However, the (new) electronic and structural properties of graphene and doped graphene sheets have attracted several studies focusing on the fundamental research.
Substitutional boron impurities are very common in graphene [2]. Those impurities may change the local electronic and structural properties of graphene in a suitable way, providing an atomic control of its interaction with external elements (atoms or molecules). For instance, hydrogen interaction with pristine or boron doped graphene sheets [3-6].
We present an ab initio study of hydrogen adsorption on boron doped graphene sheets. The calculations were performed in the framework of the density functional theory using local spin density approximation, within the supercell approach. Our total energy results reveal the formation of preferential domains, or preferential configurations, for substitutional boron atoms on graphene sheets, viz.: two substitutional boron atoms occupying opposite sites of the same hexagonal ring. This results is in contrast with the previous total energy calculations [5,6]. The proposed structural models in those references are energetically less stable by about 0.2 eV. Having determined the energetically most favorable configuration for the substutional boron atoms on graphene sheet, we next examined the hydrogen adsorption on this system. Where we find an energetic preference of hydrogen adsorption of the carbon site nearest neighbor to the substitutional boron atom. Further increase of hydrogen coverage indicates that the formation of H clusters nearby the boron substitutional sites represents the most likely configuration.
References:
[1] Serguei Patchkovki et al., PNAS 102, 10439 (2005)
[2] I. Suarez-Martinez et al., Phys. Rev. Lett. 98, 015501 (2007)
[3] L. Hornekaer et al., Phys. Rev. Lett. 97, 186102 (2006)
[4] Elizabeth J. Duplock et al., Phys. Rev. Lett. 92, 225502 (2004)
[5] Z.H. Zhu, J. Phys. Chem. B 110, 1249 (2006)
[6] Y. Ferro et al., J. Chem Phys. 118, 5650 (2003)
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