The adsorption behavior of CO on bimetallic Ni/Cu͑110͒ surfaces has been studied experimentally by thermal-desorption spectroscopy and theoretically by density-functional theory ͑DFT͒ calculations. The bimetallic surfaces were produced either by evaporation of nickel or by decomposition of Ni͑CO͒ 4 on Cu͑110͒. Adsorption of CO at 180 K on such a bimetallic surface yields three new adsorption states with adsorption energies between that of CO on clean Cu͑110͒ and clean Ni͑110͒. The new desorption peaks from the bimetallic surface, designated as  1 - 3 , can be observed at 250, 300, and 360 K, respectively. These new states are most pronounced when 1 2 monolayer of nickel is present on the copper surface. DFT calculations, using the Vienna ab initio simulation package code, were performed to identify the most probable Ni/Cu atomic arrangements at the bimetallic surface to reconcile with the experimental results. It turned out that CO adsorption on nickel dimers consisting of in-surface and adjacent subsurface atoms can best explain the observed experimental data. The result shows that CO adsorption is determined by local ͑geometric͒ effects rather than by long-range ͑electronic͒ effects. These findings should contribute to a better understanding of tailoring catalytic processes with the help of bimetallic catalysts.
The adsorption and subsequent reaction of methanol on Cu(110) and on the oxygen stripe phase on Cu(110) was investigated using reflection absorption infrared spectroscopy (RAIRS), temperature-programmed desorption (TPD) and density functional theory (DFT) calculations. It was shown that during high methanol exposures water can coadsorb and it is incorporated into the methanol rows formed in the chemisorbed layer. The RAIR spectra of adsorbed methanol are very similar with and without coadsorbed oxygen. This is due to the fact that the ν(CO) vibration is at the same frequency for both methanol and methoxy adsorbed in the more stable short-bridge site. However, methoxy adsorbed in the long-bridge site shows the ν(CO) vibration at lower wavenumbers and is found with increasing surface temperature. With coadsorbed oxygen the reaction products are formaldehyde, H 2 , and CO 2 . DFT and RAIRS results suggest that the intermediate leading to CO 2 is an η 2 -formaldehyde and OH species on the surface, rather than formate.
Integral and angle resolved thermal desorption spectroscopies were used to study methanol adsorption and oxidation on clean and oxygen covered Cu(110) surfaces. Special emphasis was put on the Cu-CuO stripe phase, which forms when the Cu(110) surface is covered with 0.25 ML of oxygen. In the temperature regime between 200 and 300 K associative desorption of methanol and water takes place, showing a normal desorption character with peaks shifting to lower temperature with increasing coverage and with a nearly cosine angular desorption distribution. In the temperature range of about 350 K formaldehyde, hydrogen, and again methanol desorb nearly concomitantly in the form of a very narrow peak (full width at half maximum=10 K), with peaks shifting to higher temperature with increasing methanol coverage. The angular distribution of these peaks is strongly forward focused, indicating activation barriers being involved. In the case of the Cu-CuO stripe phase the angular distribution of the desorption products is clearly different in the [110] and [001] azimuthal directions, demonstrating the influence of the border lines between the copper and the copper oxide stripes on the desorption process.
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