The reactivity of hydroxyl groups toward ammonia on Ni(1 1 0) surfaces

摘要: Abstract The chemistry of ammonia on Ni(1 1 0) single-crystal surfaces in the presence hydroxyl (OH) groups was characterized by temperature-programmed desorption (TPD) and X-ray photoelectron spectroscopy. Submonolayer coverages OH surface were shown to exert a strong influence thermal ammonia. In particular, NH3 TPD spectra from NH3/OH/Ni(1 1 0) display following significant changes those obtained with NH3/Ni(1 1 0) system: (1) appearance high-temperature ammonia, water hydrogen peaks at ∼400 K; (2) an overall reduction that adsorbs directly Ni sites (the α-NH3 state); (3) upward shift temperature bonded other species β-NH3 state). Although K is also seen NH3/O/Ni(1 1 0) system, α- states are much less evident there than hydroxyls. A similar behavior observed water, particularly when activated appropriate annealing prior dosing. interpreted terms adsorbing geometry bonding between adsorbed species.