Size and Topological Effects of Rhodium Surfaces, Clusters and Nanoparticles on the Dissociation of CO

The present density functional theory study provides insight into the reactivity of the surface metal atoms of extended/periodic Rh surfaces, clusters, and nanoparticles toward CO adsorption and dissociation. Our results demonstrate that the defect site in a B 5 configuration is the most active one for CO dissociation on all three considered systems. However, the reactivity of the B 5 site for CO dissociation depends critically on the size of the system. The barrier for CO dissociation barrier on the B 5 site increases for smaller particles. The lowest barrier is found for the B 5 site of a stepped Rh (211) surface. CO dissociation on this site occurred with a barrier below the desorption energy of CO.