Partial Reduction of NO to N2O on Cu{311}: Role of Intermediate N2O2

Abstract

We investigate the adsorption and reaction of NO on Cu{311} via a combination of Reflection Absorption Infrared Spectroscopy (RAIRS) and first-principles Density Functional Theory (DFT), providing a mechanistic understanding of the reaction as it progresses. Our results support an interpretation that N2O is formed via an associative mechanism involving N2O2 as the crucial intermediate species. Consistent with previous work, we find that such an intermediate readily converts between its initial nitrogen-down configuration and an inverted oxygen-down configuration, prior to decomposition by cleavage of a single N-O bond. As the reaction proceeds, the surface is progressively poisoned by the accumulation of O adatoms resulting from N-O bond scission, and we probe this aspect of the reaction in detail as a function both of temperature and of the surface’s pre-exposure to oxygen. Our results indicate that sustained conversion of NO to N2O on Cu would be contingent upon identifying some co-reactant capable of continuously removing O from the surface as the reaction proceeds