A theoretical study of the CO and NO chemisorption on Cu2O(111)

The density functional theory coupled to the molecular cluster approach has been used to study the bonding of CO and NO to the Cu2O(111) non-polar surface. Two molecular orientations, X-and O-down (X=C, N), at two distinct sites, mono-and three-coordinated, of the Cu2O(111) surface have been considered. Theoretical outcomes indicate that the former coordinative position is more favoured than the latter and that the X-down bonding is definitely stronger than the O-down one. Both XO-->Cu(I) sigma donation and Cu(I)-->XO pi backdonation participate in the adsorbate/substrate interaction. In agreement with literature experimental results, the C-O and N-O stretching frequencies are significantly red-shifted upon coordination. (C) 1997 Elsevier Science B.V.