Adsorption and reaction of carbon dioxide on pure and alkali-metal promoted cold-deposited copper films

Abstract

The adsorption and reaction of carbon dioxide on pure and potassium-doped cold-deposited copper films has been investigated at low temperatures and under UHV conditions using surface enhanced Raman spectroscopy (SERS) and X-ray photoemission spectroscopy (XPS). On pure copper films, an activated anionic CO δ− 2 species has been observed in addition to a weakly physisorbed CO 2 species. On potassium-doped copper films, monodentate carbonate as well as carbon monoxide has been observed in addition to the two carbon dioxide species. After adsorbing CO 2 on preadsorbed hydrogen, weak features at 2841 and 2949 cm −1 indicate the formation of formate. This result is compared to formate on pure copper films, synthesised by adsorbing formic acid on preoxidised copper films and subsequent annealing to 200 K.