Theoretical studies of N2O adsorption and reactivity to N2 and NO on Rh(111)

Periodic DFT calculations have been performed to investigate the adsorption, activation, and reactivity of N2O on a Rh(111) surface. Several adsorption modes in a narrow range of energies have been found. The most stable situation corresponds to a weak bonding (0.39 eV) via the N-terminal atom on top of a Rh atom, with the lineal N2O molecule situated nearly perpendicular to the surface. Other flat adsorption modes via the two N atoms or the terminal N and O atoms have also been identified, with adsorption energies around 0.20 eV. These modes activate the molecule by weakening the N-O or N-N bonds, leading to its dissociation and subsequent formation of N-2 or NO. Mechanisms leading to these products have been analyzed, identifying the intermediates and transition states. Both pathways were found to be exothermic but decomposition to N-2 presents significantly lower activation barriers and higher kinetic constants.