A DFT study of CO catalytic oxidation by N2O or O2 on the Co3O4 (110) surface

Abstract

The reaction mechanisms for CO catalytic oxidation by N2O or O2 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 O2 interacts with the oxygen vacancy site to regenerate the surface, leaving N 2 or the activated O2- species to be attacked by the second CO to yield CO2 to proceed with the catalytic cycle. The CO oxidation reaction follows the Mars-van Krevelen mechanism. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.