Theoretical insights into the reaction mechanisms of NO oxidation catalyzed by Cu2O(111)

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 + O-2* -> 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, O-2 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. (C) 2014 Elsevier B.V. All rights reserved.