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, N(2)O and NO(2), 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 N(2). At a large coverage, the recombination of N and NO to form N(2)O is favorable; this species might either desorb or break the N-O bond to form N(2). Our calculated results agree satisfactorily with experimental observations. The formation of N(2)via paths that vary with coverage is analyzed and discussed.