N2O dissociation on small Rh clusters: A density functional study

Abstract

Density functional theory calculations are performed on Rh1–6 clusters to study N2O adsorption and dissociation as a model for the N2O decomposition reaction. For Rh1–6N2O clusters the molecular precursor adsorptions are found to occur at the bridge sites and on certain top sites. For all clusters, N2O decomposition initiated by N–O bond breaking is more favorable to form N2 and O as the final products. Dissociative adsorptions are energetically prefered for Rh1–6N2O clusters and the adsorption energy increases with cluster size. The N2O dissociation process involves a small barrier for Rh1–4 clusters, and it is found barrierless, for dissociations on Rh5–6 clusters. The relevant magnetic moments of the Rh1–6 clusters interacting with N2O are discussed. For comparison when going to larger clusters, we have also calculated the N2O dissociation taking place on the Rh(111) surface. We found that both on the Rh clusters as well as on the Rh(111) surface the N2O catalytic dissociation is possible.