Graphene on Rh(111): A template for growing ordered arrays of metal nanoparticles with different periodicities

The development of approaches to provide ordered networks of metal nanoparticles is a topic of great interest due to its potential contribution to the advent of a more efficient technology. The template-assisted formation of ordered nanoparticle arrays on graphene- or h-BN-metal surfaces has profiled as a promising approach because of the periodic interfacial modulations associated to the moire patterns. Nevertheless, a complete understanding of the requirements that a moire must meet to act as a good template is still challenging. In order to shed light on this issue, here, the graphene/Rh(111) surface is investigated as model template for the growth of metal nanoparticles due to its large variety of moire patterns. Scanning tunneling microscopy experiments have revealed different Ir nanoparticle spatial distributions depending on the underlying moire periodicity ranging from randomly scattered nanoparticles to well-ordered lattices with multiple periodicities. To unveil the origin of this behavior, density functional theory calculations have been performed on representative moire patterns for the adsorption of both Ir individual adatoms and nanoparticles. We conclude that the presence of distinctive chemical environments throughout the moire, which controls the size and the adsorption configuration of the nanoparticles, is crucial for the formation of ordered arrays. (C) 2020 Elsevier Ltd. All rights reserved.