Formation of Pt islets on facets of Ru nanoparticles: a first-principles   study
  We have carried out density functional theory based calculations of the size dependent formation energy and geometry of Pt islands on Ru(0001), to model Pt-Ru nanocatalysts which have been recently proposed as fuel cell anode. The Pt islands are found to prefer two-dimensional structures. Furthermore, a monotonic decrease in the formation energy per Pt atom suggests a propensity of Pt atoms to wet the Ru(0001) surface. Calculated energy barriers for the diffusion of Pt monomers and dimers on the facets and through the edges of a superstructure modeling a Ru nanoparticle indicate that these edges help reduce considerably the diffusion rates across them such that the Pt atoms prefer to remain in the facet on which they were adsorbed originally and form 2D islands. 
Marisol Alc\'antara Ortigoza, Sergey Stolbov, Talat Rahman