A DFT Study of CO Catalytic Oxidation by N2O or O2 on the Co3O4(110) Surface

The reaction mechanisms for CO catalytic oxidation by N2O or O-2 on the Co3O4(110) surface were studied by DFT slab calculations. CO chemisorbs preferably at a surface Co3+ site. After the Co3+ site is completely covered, CO adsorbs at the neighboring twofold coordinated surface oxygen atom bonded to Co2+ and Co3+ cations, resulting in the formation of CO2 and an oxygen vacancy with a low energy barrier of 0.033 eV, which rationalizes the experimental observation that Co3O4-based systems are active for CO oxidation at low temperatures. N2O or O-2 interacts with the oxygen vacancy site to regenerate the surface, leaving N-2 or the activated O-2(-) species to be attacked by the second CO to yield CO2 to proceed with the catalytic cycle. The CO oxidation reaction follows the Marsvan Krevelen mechanism.