Dissociation of molecular oxygen on unpromoted and cesium-promoted Ag(111)surfaces

Density functional calculations for the dissociation of molecular oxygen on a Ag-10 cluster model (seven surface and three subsurface atoms) of the [1 11] surface of silver are presented. The calculations show that the reactio n pathway for the dissociation of molecular oxygen depends on the amount of cesium present on the surface. For the unpromoted surface, dissociation sh ould have a low rate as the process is activated. As a single Cs atom is ad ded to the cluster, O-2 should readily dissociate since the process is kine tically and thermochemically favored. However, as a second Cs atom is added , the dissociation of O-2 is quenched as the process is highly activated.