Mechanisms of CO Oxidation on Oxygen Pre-Dosed Ni(111) Surfaces

The mechanisms of CO oxidation on Ni(111) surfaces pre-dosed with Oxygen are systematically investigated using a combination of UHV experimental (XPS, TPD, STM) and first-principles (DFT) methods. Different CO oxidation mechanisms on Ni(111) surfaces with local O-islands, O chemisorbed on Ni(111) as a function of surface coverage up to 1 ML, and on highly oxidized Ni(111) surfaces, i.e., NiO(111) surfaces, are discussed. These different CO oxidation mechanisms can be used to rationalize experimental results on CO oxidation on Ni(111) surfaces under different experimental conditions. Insights derived should be applicable to CO oxidation on other transitional metal surfaces.