Interactions of O 2, CO, CO 2, and D 2 with the stepped CU(311) crystal face: Comparison to CU(110)

Abstract

Carbon dioxide is shown to chemisorb and dissociate to carbon monoxide and atomic oxygen on Cu(311) at 150 K in ultra-high vacuum. The reverse reaction of carbon monoxide and surface oxygen to form carbon dioxide is also shown to occur in the range of 150 to 400 K. At about 0.4 ML oxygen on Cu(311), a poorly ordered p(2 × 1) surface structure forms. Increasing the oxygen coverage further enhances surface disorder. Oxygen blocks only one of the three CO adsorption sites, and has little effect on CO 2 adsorption and dissociation. Adsorption of D 2 on Cu(311) is enhanced by pre-adsorbed oxygen. We contrast the high reactivity of Cu(311) for CO 2 and D 2 dissociative adsorption, and for CO oxidation to CO 2 with the relatively inactive Cu(110). These chemisorption studies suggest that methanol synthesis over copper may be a structure sensitive reaction.