Semi-empirical 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-doping on the edge and internal lattice sites of the graphene layer produces very different effects on the electronic structure around the edges. It is found that the substitutional boron atoms on the edges dramatically alter the density distribution of high energy electrons along the edges and the substitutional boron atoms in the deep internal lattice sites do not produce any significant effect on the density distribution along the edges. Based on the results obtained, a model is proposed for describing the oxidation process in boron-doped graphite. The mechanism of oxidation inhibition due to boron-doping of a graphene layer is chemical inhibition via the reduction of electron density with high energy at surface sites, and consequently, a reduction in the total number of active sites for gasification of the carbon. (C) 1997 Elsevier Science Ltd.