Absence of Subsurface Oxygen Effects in the Oxidation of Olefins on Au: Styrene Oxidation over Sputtered Au(111)

The influence of subsurface oxygen and surface roughness on the selectivity and activity for styrene oxidation was investigated on Au(111). Buried oxygen and a rough surface morphology was created by O-2(+) sputtering of Au(111). Surface roughness was specifically investigated by creating a similarly rough surface morphology using Ar+ sputtering and subsequently oxidizing with ozone. Styrene oxidation, which has been previously studied on oxidized Au(111), was used as a probe reaction. The major products of styrene oxidation are styrene epoxide, benzoic acid, CO2, and water. Subsurface oxygen does not significantly affect either the product distribution or the overall amount of styrene conversion. Surface roughness leads to an increase of the overall amount of styrene that is oxidized and reduces the selectivity for, styrene epoxidation. Compared to well-annealed Au(111), 50-100% more benzoic acid and CO2 are formed on Ar+-sputtered Au(111) oxidized by ozone. At the same time, the styrene epoxide yield is essentially the same for both surfaces.