First-principles study of dissociation barriers and electronic structures of monolayer graphite on Ni(1 1 1) surface

Abstract

To evaluate the dissociation possibility of graphite upon nickel catalyst, we investigated the structure, dissociation barriers of the monolayer graphite and the monolayer graphite on Ni(1 1 1) surface using the first-principles method based on the plane-wave basis set. Electronic structures of both the reactants and dissociation products were calculated as well. We used two different dissociation product models to study the dissociation barriers of monolayer graphite on Ni(1 1 1) surface, and the free monolayer graphite dissociation model was also built for comparison. It was found that the dissociation barrier decreased from 15.4 to 10.6 eV when the monolayer graphite was adsorbed on Ni(1 1 1) surface. Moreover, we found a much lower barrier of 5.0 eV for the incomplete dissociation of monolayer graphite on Ni(1 1 1) surface. Partial density of states for the free graphite and the adsorbed graphite on Ni(1 1 1) surface revealed that the majority of the bonding of carbon atoms is carbon–carbon bonding, as apposed to bonding of carbon atom to the nickel surface in the dissociation products. In particular, the carbon atoms in the dissociation products have obvious C(2s+p) hybridized bonding and non-bonding electrons. The results indicated that although graphite is such a stable material with high melting point of 4800 K, nickel catalyst can make it relatively easy to completely or incompletely dissociate to a great extent, especially along the special dissociation paths.