Coadsorption of CO and O2 on Pd(1Â 1Â 1)

We studied the adsorption of O2 on a CO-precovered Pd(1 1 1) surface using density functional theory. The main purpose of this study was to get more information on the dissociation of O2 and to compare precursor states and dissociation barriers with those on the clean surface. We found that the dissociation became more difficult in coadsorption than on clean surface. One clear precursor state for dissociation was found in this study. In coadsorption the dissociation of O2 took place along the top channel. Some earlier theoretical and experimental results on adsorption and dissociation are discussed.