A DFT study of molecular adsorption on Au-Rh nanoalloys

Abstract

Density functional theory calculations are performed to investigate both mixing and adsorption properties of 38-atom and 79-atom Au-Rh nanoalloys at the nanoscale. The RhcoreAushell and RhballAucup isomers are found to be energetically favourable with respect to other isomers. The adsorption strengths of reactive species such as H2, O2 and CO are found to be greater on the Rh part than on the Au part of the nanoalloys and therefore a core-shell inversion is found to be feasible under a molecular environment. It is also found that underlying Rh atoms decrease the adsorption strength on the Au part whereas underlying Au atoms increase it on the Rh part of the nanoalloys. The strain, alloying and relaxation effects on adsorption strength are characterized using a sequential approach and their competing nature is demonstrated for the Au-Rh bimetallic system.