| Abstract
| - The activation of dioxygen via dissociation on strained and stepped gold surfaces has been studied usingperiodic self-consistent (GGA-PW91) density functional theory (DFT) calculations. Although we find thatmolecular oxygen does not adsorb on Au(111), it does bind, albeit weakly, to an Au(111) surface stretchedby 10% as well as to Au(211) surfaces both stretched and unstretched. The most stable molecular states onall three surfaces have the top−bridge−top configuration and carry about half of the magnetic moment ofgas-phase O2. On 10%-stretched Au(111), unstretched Au(211), and 10%-stretched Au(211), the bindingenergies of O2 are −0.08, −0.15, and −0.26 eV, respectively, and the activation energies of O2 dissociationare 1.37, 1.12, and 0.63 eV. Both steps and tensile strain enhance the adsorption of atomic and molecularoxygen. A comparison between unstretched and stretched Au(211) indicates that the enhancing effect oftensile strain is less pronounced on the step edge than on the flat terrace. The magnitude of the dissociationbarriers, combined with the fact that the transition states lie above the gas-phase zero on all three surfaces,suggests that O2 dissociation remains an activated process on gold. Although additional factors may be involvedin O2 activation at low temperatures on oxide-supported Au catalysts, the present work shows that steps andtensile strain substantially facilitate O2 activation on Au surfaces.
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