Plane-wave pseudopotential density functional theory periodic slab calculations of CO adsorption on Cu₂O(1 1 1) surface

Plane-wave pseudopotential Density Functional Theory (DFT) periodic slab calculations have been performed to investigate carbon monoxide adsorption on the (1 1 1) surface of Cu₂O. Negligible relaxation of this surface was found (surface energy = 0.71 J m^-2), consistent with its non-polar nature. The on-top-Cu site of CO adsorption is favoured, with a binding energy of 1.50 eV. After adsorption, the Cu-C bond distance was found to be 1.82 Å and that of C-O was 1.15 Å. From the Density of States (DOS) plots, a distinct stabilization of both the Cu 3d and CO 5σ is observed with predominant back-bonding to CO 2π* from Cu. A red shift of -26 cm^-1 in the C-O stretch was found in good agreement with experimental results.