Stable AA-Stacked Pt Nanoclusters Supported on Graphene/Ru(0001) and the Selective Catalysis: A Theoretical Study

Most metals with close packed atomic arrangements have been found to adopt ABC- or AB-stacking, since this arrangement affords the largest possible coordination number of 12. Here, based on first-principles calculations, we report for the first time the predicted high stability of AA-stacked Pt nanoclusters when supported on a graphene/Ru(0001) surface. Our theoretical analysis reveals that this unusual AA stacking is favored due to chemical bonding between Pt atoms and graphene on Ru(0001) surface, where vertically aligned p(z) orbitals of C atoms tend to hybridize with the d(z)(2) orbitals of the Pt atoms in the bottom most layer in the cluster. Consequently, d(z)(2)-d(z)(2) bonding between Pt layers is induced, leading to AA-stacking sequence in the Pt nanoclusters. Further analysis proves that these supported AA-stacked Pt clusters interact with adsorbed molecules or radicals in different strength and can, therefore, serve as high-selectivity catalysts for various applications.11scopu