Graphene Adhesion Mechanics on Iron Substrates: Insight from Molecular Dynamic Simulations

L Wang and JF Jin and PJ Yang and YP Zong and Q Peng, CRYSTALS, 9, 579 (2019).

DOI: 10.3390/cryst9110579

The adhesion feature of graphene on metal substrates is important in graphene synthesis, transfer and applications, as well as for graphene- reinforced metal matrix composites. We investigate the adhesion energy of graphene nanosheets (GNs) on iron substrate using molecular dynamic (MD) simulations. Two Fe-C potentials are examined as Lennard-Jones (LJ) pair potential and embedded-atom method (EAM) potential. For LJ potential, the adhesion energies of monolayer GN are 0.47, 0.62, 0.70 and 0.74 J/m(2) on the iron 110, 111, 112 and 100 surfaces, respectively, compared to the values of 26.83, 24.87, 25.13 and 25.01 J/m(2) from EAM potential. When the number of GN layers increases from one to three, the adhesion energy from EAM potential increases. Such a trend is not captured by LJ potential. The iron 110 surface is the most adhesive surface for monolayer, bilayer and trilayer GNs from EAM potential. The results suggest that the LJ potential describes a weak bond of Fe-C, opposed to a hybrid chemical and strong bond from EAM potential. The average vertical distances between monolayer GN and four iron surfaces are 2.0-2.2 angstrom from LJ potential and 1.3-1.4 angstrom from EAM potential. These separations are nearly unchanged with an increasing number of layers. The ABA-stacked GN is likely to form on lower-index 110 and 100 surfaces, while the ABC-stacked GN is preferred on higher-index 111 surface. Our insights of the graphene adhesion mechanics might be beneficial in graphene growing, surface engineering and enhancement of iron using graphene sheets.

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