Formation of Pt islets on facets of Ru nanoparticles: a first-principles study

TL;DR

This study uses density functional theory to analyze how platinum forms islets on ruthenium nanoparticle facets, revealing preferences for 2D structures and the role of edges in atom diffusion, relevant for fuel cell catalysts.

Contribution

It provides first-principles insights into Pt island formation on Ru nanoparticles, highlighting the influence of surface facets and edges on atom diffusion and island morphology.

Findings

Pt islands prefer two-dimensional structures.

Pt atoms tend to wet the Ru(0001) surface.

Edges significantly reduce Pt atom diffusion across facets.

Abstract

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.