The interaction of NO_x on Ni(111) surface investigated with quantum-chemical calculations

We applied periodic density-functional theory to investigate the interaction of NO_x on Ni(111) surface for small and large coverages. For a small coverage, adsorbed species, such as NO, N₂O and NO₂, tend to dissociate to form atomic N and atomic O on the surface, but a large barrier, 2.34 eV, hinders the recombination of adsorbed N to form N₂. At a large coverage, the recombination of N and NO to form N₂O is favorable; this species might either desorb or break the N-O bond to form N₂. Our calculated results agree satisfactorily with experimental observations. The formation of N₂via paths that vary with coverage is analyzed and discussed.