Redistribution of π and σ electrons in boron-doped graphene from DFT investigation

Abstract

Physical properties are closely associated with the variation of electronic states. This work provides a theoretical analysis of Pi (π) and Sigma (σ) electron redistribution in boron-doped graphene by density functional theory (DFT). An energy gradient appears for π electrons which homogeneously distributed in pristine graphene evolving into a distribution with energies gradually decreasing from the substitutional boron to further carbon atoms. The introduction of boron not only affects the distribution of π electrons but also σ electrons. An increasing boron concentration makes σ electrons changed from localized states to delocalized states, which is attributed to the impurity bands caused by the formation of BC and BB bonds. An opposite charge transfer direction for π and σ electrons (from C to B and B to C, respectively) is observed which further confirms that the substitutional boron in graphene acts as the π acceptor and σ donor. A better understanding of redistribution of electrons in graphene is either as the prerequisite to explore the root cause of change in microscopic properties or as a foundation for further application of dopants doped graphene or carbon materials.