Indexed on: 23 Mar '17Published on: 14 Mar '17Published in: Carbon
Graphene is a promising material for a number of technological applications due to its unique electronic properties. It can be mass produced by depositing carbon atoms on metal scaffolds, such as nickel. This work presents a detailed study of graphene adsorption on the nickel (111) surface using the exchange-hole dipole moment (XDM) dispersion correction. XDM is shown to accurately model graphene-nickel interactions, providing adsorption energies in excellent agreement with available experimental data and with RPA calculations. All six graphene-nickel orientations studied present a physisorption energy minimum, but only three exhibit chemisorption. The physisorption and chemisorption minima are close in energy, and are separated by a barrier of ∼1 kJ/mol per carbon. The relative strength of the chemisorption and physisorption interactions is found to depend heavily on the nickel lattice constant. Thermal expansion stabilizes chemisorption relative to physisorption. The pairwise dispersion coefficients depend strongly on the graphene-nickel distance, and their variation is determined by the exchange-hole dipole moments. If this dependence of the dispersion coefficients with the environment is properly captured, a pairwise dispersion correction (like XDM) is suitable to model surface adsorption.