Adsorption of carbon dioxide on Cu(110) and on hydrogen and oxygen covered Cu(110) surfaces

Abstract

The interaction of CO₂ with a clean Cu(110) surface and with pre-adsorbed oxygen and hydrogen on this surface has been studied in ultra-high vacuum at temperatures between 20 and 500 K with temperature programmed thermal desorption, low-energy electron diffraction, Auger electron spectroscopy, high-resolution electron energy loss spectroscopy and work function change measurements. CO₂ adsorbs only molecularly on the clean and on the hydrogen(1×2) and oxygen(2×1) reconstructed Cu(110) surface, respectively. The initial sticking probability of CO₂ is not affected by co-adsorption of oxygen or hydrogen, although the CO₂ adsorption is energetically stabilised in this case by 1.3 and 5.4 kJ mol^-1, respectively. On clean Cu(110), the isosteric heat of adsorption rises with coverage from ∽13 to 25 kJ mol^-1 at saturation. High-resolution electron energy loss spectroscopy suggests that the isolated carbon dioxide molecule is adsorbed in a linear configuration on the clean and on the reconstructed surfaces, while for coverages >0.1 three-dimensional clustering occurs. Our experiments reveal that neither dissociation into oxygen and carbon monoxide nor hydrogenation of carbon dioxide occurs under the experimental conditions.