Boron-Doped, Nitrogen-Doped, and Codoped Graphene on Cu(111): A DFT + vdW Study

The electronic properties of free-standing and Cu-supported pristine and boron-doped, nitrogen-doped, and codoped graphene have been studied by means of density functional theory (DFT) with the vdW-DF2(C09x) functional. The effects of substitutional chemical doping, metal support, lattice parameter strain, and their eventual interplay have been investigated. We find that only boron-doped graphene strongly interacts with the copper substrate, due to chemical bonds between the boron atom and the underlying metal. The binding energy and charge transfer from Cu are also highly enhanced compared to both pristine and nitrogen-doped supported graphene. The BN codoped system behaves similarly to pristine graphene with a weakly physisorbed state and a small charge transfer from Cu. However, the presence of the nonmetal dopants makes the codoped sheet extremely tunable for redox purposes, with the boron site acting as an electron acceptor and the nitrogen site as an electron donor.