Migration of adatom adsorption on graphene using DFT calculation

DFT calculations of various atomic species on graphene sheet are investigated as prototypes for the formation of nano-structures on graphene. We investigate computationally the adsorption energies and migration energies in adsorption sites on graphene sheet for many atomic species, including transition metals, noble metals, nitrogen and oxygen, from atomic number 1 to 83, using the DFT calculation. The calculations are done for adatoms at three sites having symmetry, H6, B and T on a 3×33×3 super cell. For adsorption energy and migration energy, we performed a study that covered almost all the periodic table. The calculated results show that adsorption for metal and transition metal elements is mainly on the H6-site, whereas nonmetallic elements showed a tendency to adsorb on the B-site. When we consider a metal–graphene junction, not only the adsorption energy but also the migration energy is important. We estimate the minimum limit of the migration energy of the adatom. We found that 3d transition metals and some nonmetallic elements had very high migration energy. Our calculation will be very helpful for experimental groups that are considering the choice of electrode materials for metal–graphene junctions, and in designing nano devices, nano wires and nano switches.

Research highlights
► The adsorption energy was calculated for adatoms from most of the periodic table.
► The migration energy was calculated for adatoms from most of the periodic table.
► The relation between bond energy and bond distance was discussed.
► The junction of metal–graphene was discussed.