Adsorption states of carbon monoxide on oxygenated Cu(110) faces

Abstract

Oxygen preadsorption on Cu(110) surfaces strongly reduces the CO desorption peak at 220 K, typical for clean Cu(110) and induces the development of less tightly bound states, which probably correspond to sites on Cu(111) micro-facets, formed in the course of oxygen stimulated surface reconstruction. A smaller part of the CO molecules (⩽ 20%) seems to interact with adsorbed oxygen to give adsorbed CO 2 − which can be stabilized in the presence of CO2 by formation of van der Waals complexes, e.g. [CO2 · CO 2 − ]. At increasing temperature this complex decomposes or disproportionates to give desorbing CO and adsorbed CO 3 − . The interpretation is tentative, but some evidence is given to it by TDS from Cu(111), by XPS, STM and SIMS studies and by theoretical calculations.