Abstract
The adsorption behavior of CO on bimetallic Ni/Cu(110) surfaces has been studied experimentally by thermal-desorption spectroscopy and theoretically by density-functional theory (DFT) calculations. The bimetallic surfaces were produced either by evaporation of nickel or by decomposition of on Cu(110). 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 Cu(110) and clean Ni(110). The new desorption peaks from the bimetallic surface, designated as , can be observed at 250, 300, and 360 K, respectively. These new states are most pronounced when 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 (geometric) effects rather than by long-range (electronic) effects. These findings should contribute to a better understanding of tailoring catalytic processes with the help of bimetallic catalysts.
7 More- Received 14 April 2009
DOI:https://doi.org/10.1103/PhysRevB.80.085421
©2009 American Physical Society