Dissociative chemisorption of CH4 on Ni(100) with preadsorbed oxygen

The dissociative chemisorption of CH4 on Ni(100) with preadsorbed oxygen has been studied in the temperature range of 450–600 K. using XPS to monitor surface concentrations. The carbon growth curves can be explained by each carbon and oxygen adatom blocking five sites for the chemisorption of CH4. The oxygen coverage θO remains constant during CH4 exposure at temperatures below 500 K. At higher temperatures θO is diminished during CH4 exposure due to reaction with carbon adatoms and due to migration of oxygen atoms below the surface. No evidence is seen for enhanced sticking of CH4 when oxygen atoms are present on the nickel surface as has been reported in the literature.

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