On the Mechanism of Low-Temperature CO Oxidation on Ni(111) and NiO(111) Surfaces

Abstract

Through an interplay between density functional theory and scanning tunneling microscopy, we investigated the mechanism of low-temperature CO oxidation on Ni(111) and NiO(111) surfaces. We systematically examined CO oxidation on different possible active sites. We find that sub- and full monolayers of O chemisorbed on Ni(111) surfaces play no significant role in low-temperature CO oxidation. We further show that CO oxidation at the perimeter of O islands on Ni(111) cannot occur at low temperatures. In contrast, we suggest that oxidized Ni(111) surfaces, i.e., NiO(111), can catalyze low-temperature CO oxidation when NiO(111) is saturated by O2. Our findings can rationalize low-temperature CO oxidation on Ni(111) surfaces that have been predosed with large amounts of oxygen, as observed in recent experiments.