SEMIEMPIRICAL STUDIES ON ELECTRONIC-STRUCTURES OF A BORON-DOPED GRAPHENE LAYER - IMPLICATIONS ON THE OXIDATION MECHANISM

The electronic structures of pure and boron-doped graphene layers have been investigated using the semi-empirical Molecular Orbital Package (MOPAC) and large clusters of carbon atoms. It is shown that boron-dop ing on the edge and internal lattice sites of the graphene layer produ ces very different effects on the electronic structure around the edge s. It is found that the substitutional boron atoms on the edges dramat ically alter the density distribution of high energy electrons along t he edges and the substitutional boron atoms in the deep internal latti ce sites do not produce any significant effect on the density distribu tion along the edges. Based on the results obtained, a model is propos ed for describing the oxidation process in boron-doped graphite. The m echanism of oxidation inhibition due to boron-doping of a graphene lay er is chemical inhibition via the reduction of electron density with h igh energy at surface sites, and consequently, a reduction in the tota l number of active sites for gasification of the carbon. (C) 1997 Else vier Science Ltd.