Structural and kinetic effects on a simple catalytic reaction: Oxygen reduction on Ni(110)

摘要: Oxygen hydrogenation at 100 K by gas phase atomic hydrogen on Ni(110) has been studied under ultrahigh vacuum conditions temperature programmed desorption (TPD) and x-ray photoelectron spectroscopy (XPS). Formation of adsorbed water hydroxyl species was observed characterized. The coverage the reaction products monitored as a function both initial oxygen precoverage. On contrary, when high overlayers were exposed to molecular hydrogen, no took place. results are compared inverse process, exposing covered surface oxygen. In this case, K, simple Langmuir-Hinshelwood modeling yields an sticking coefficient for adsorption equal 0.26, considerably lower than clean surface. Moreover, formation groups is found be twice fast final OH water. Assuming preexponential factor 10(13) s(-1), activation barrier 6.7 kcal/mol obtained formation, thus confirming hydrogenating activity nickel with respect other transition metals, which higher energies reported. However, hardly removed nickel: explained basis strong Ni-O chemical bond. residual well described including contribution from adsorption-induced H process takes place during uptake clearly visible TPD data.