Coadsorption of CO and NO on the Cu2O(111) surface: A periodic density functional theory study

Coadsorption of carbon monoxide (CO) and nitric oxide (NO) on the Cu2O(111) surface was studied using periodic density functional theory calculations. It is interesting to find that CO+NO on Cu2O(111) could react to form adsorbed NCO surface species. Coadsorption of CO and NO could give rise to the formation of a O-C center dot N-O complex well bound to the Cu2O(111) surface, in which both the C-O and N-O bonds are greatly activated and the C-N bond is formed. Consequently, the reaction of CO with NO to form adsorbed NCO and CNO species may occur, for which it is disclosed that NCO formation is more possible than CNO formation both thermodynamically and kinetically. In addition, our calculations of searching transition states reveal that it is facile for NCO formation both kinetically and thermodynamically when CO+NO reaction takes place at Cu-CUS site, and is impossible when this reaction takes places at O-vac site. Moreover, CO2 species cannot form when CO+NO reaction occurs at O-vac site. Therefore, oxygen vacancy on Cu2O(111) does not play a positive role on CO+NO reaction to forming NCO, CNO, or CO2 species.