Interaction of silica-supported small silver clusters with molecular oxygen. A computational study

Abstract The effect of nonbridging oxygen centers (NBOs) of a silica surface on the interaction of O 2 with small Ag n clusters ( n  = 3,4) has been studied computationally, using a scalar relativistic density functional method and embedding in an elastic polarizable environment described by molecular mechanics. Two types of O 2 adsorption, molecular and dissociative, were analyzed. The electrostatic interaction of the metal clusters with the silica surface stabilizes adsorbed oxygen species, particularly those obtained via dissociative adsorption. O 2 dissociation seems feasible on both silver clusters, Ag 3 and Ag 4 , but relatively high activation barriers render O 2 dissociation less probable than O 2 desorption.