Theoretical insights into the reaction mechanisms of NO oxidation catalyzed by Cu2O(1Â 1Â 1)

The NO oxidation on Cu2O(1 1 1) with molecular oxygen, dissociated oxygen, and lattice O, was studied by using periodic density functional theory. Cu2O could promote NO oxidation via the more favorable Elay-Rideal mechanism. For NO oxidation with molecular oxygen, path II (NO + O2* → O*ONO → NO2 + O*; NO + O* → NO2* → NO2) was found as the most probable route, in which NO2 desorption is the reaction rate determining step. The NO oxidation reaction with dissociated oxygen is also possible. In this case, O2 dissociation occurs after surpassing a barrier of 105 kJ/mol. Thereafter, NO molecule can readily react with oxygen adatoms without barrier or with a moderate-low barrier of 49 kJ/mol. Both of the produced NO2 molecules will release from the surface. The barrier to be surmounted is 53.3 and 103.2 kJ/mol, respectively. The reaction of NO with lattice O has a high barrier and it is very unlikely. The present results enrich our understanding of the catalytic oxidation of NO by metal-oxide catalysts.