A systematic study of CO oxidation on metals and metal oxides: density functional theory calculations.

CO oxidation on Ru(0001), Rh(111), Pd(111), Os(0001), Ir(111), Pt(111), and their corresponding metal oxides is studied using density functional theory. It is found that (i) the reactivity of metal oxide is generally higher than that of the corresponding metal, and (ii) on both metals and metal oxides, the higher the chemisorption energy is in the initial state, the larger the reaction barrier. The barriers are further analyzed by decomposing them into electronic and geometric effects, and the higher reactivity of metal oxides is attributed mainly to the surface geometric effect. Moreover, the electronic effect on both metals and metal oxides follows the same pattern: the shorter the OC-O bond distance in the TS, the higher the barrier.