Catalytic properties of F-centres at the magnesium oxide surface: Hydrogen abstraction from methane

Surface defects on MgO are known to be involved, as active sites, in the catalytic abstraction of hydrogen from methane. The energetics for the formation at the (001) surface of some of these defects, as well as their electronic structure and reactivity, are explored. In particular, F-centres (anion vacancies with two electrons trapped), Li+/F+ couples (a vacancy with one electron coupled to a substitutional Li ion) and the step (where cations and anions are four-fold coordinated) are examined. This study is complementary to a previous investigation, where the activity of Li+/O- ionic couples has been considered. In all the cases examined the reaction results to be endothermic at 0 K and F-centres are less reactive than the O- sites in the doped substrate.