| AVS 55th International Symposium & Exhibition | |
| Surface Science | Tuesday Sessions |
| Session SS1+NC-TuA |
| Session: | Reactions on Gold and BiMetallics |
| Presenter: | J.L. Gong, University of Texas at Austin |
| Authors: | J.L. Gong, University of Texas at Austin R.A. Ojifinni, University of Texas at Austin N.S. Froemming, University of Texas at Austin T. Yan, University of Texas at Austin G. Henkelman, University of Texas at Austin C.B. Mullins, University of Texas at Austin |
| Correspondent: | Click to Email |
The reactivity of atomic oxygen on Au(111) has been investigated employing molecular beam scattering and temperature programmed desorption (TPD) techniques under ultrahigh vacuum (UHV) conditions. We demonstrate that adsorbed O atoms (Oad) facilitate NH3,ad decomposition even though ammonia does not dissociate on the clean Au(111) surface. The selectivity of the catalytic oxidation of ammonia to N2 or to NO on Au(111) is tunable by the amount of atomic oxygen pre-covering the surface. Both N2 and NO are formed via simple recombination reactions (Nad + Nad and Nad + Oad). At low oxygen coverages (θO < 0.5 ML), adsorbed ammonia is stripped to NHx,ad which decomposes to form gaseous N2. We also present experimental and density functional theory (DFT) calculation results of formation and decomposition of the carbonate anion (CO3 = CO2 + Oa) on atomic oxygen pre-covered Au(111). A reaction probability on the order of 10-4 and an apparent activation energy of -0.15 eV are estimated for this reaction. The small values of reaction probability are likely part of the reason why an earlier study on Au(111) reported undetectable surface carbonate formation. Additionally, we have investigated partial oxidation of propanol on atomic oxygen covered Au(111). At reaction temperatures below 300 K, 1-propanol is oxidized to propaldehyde with 100% selectivity while acetone is the only products of 2-propanol partial oxidation. A small amount of CO2 is formed at higher surface temperatures (i.e., above 300 K).