| AVS 54th International Symposium | |
| Surface Science | Tuesday Sessions |
| Session SS1-TuA |
| Session: | Bimetallics and Alloys |
| Presenter: | J. Knudsen, University of Aarhus, Denmark |
| Authors: | J. Knudsen, University of Aarhus, Denmark L.R. Merte, University of Aarhus, Denmark R.T. Vang, University of Aarhus, Denmark A. Resta, Lund University, Sweden J. Schnadt, Lund University, Sweden J.N. Andersen, Lund University, Sweden F. Besenbacher, University of Aarhus, Denmark |
| Correspondent: | Click to Email |
In the early 1990s our group showed that deposition of gold onto nickel single-crystal surfaces results in the formation of a stable alloy in the crystal’s topmost layer, a surprising discovery considering that the two metals are immiscible in the bulk. This surface alloy was later shown to display interesting catalytic properties; for example, the presence of small amounts of gold in nickel catalysts hinders graphite formation during steam reforming of hydrocarbons.1 Other studies explored the use of gold to inhibit CO dissociation on Ni(111) and the stability of the surface alloy under high-pressure conditions.2 Most recently, Lahr and Ceyer reported that the Au/Ni(111) surface alloy catalyzes oxidation of CO to CO2 at temperatures as low as 70K.3 They conclude that gold atoms substituted into the top layer of the Ni(111) surface stabilize chemisorption of a reactive, non-dissociated O2 species in a similar manner as has been reported for gold nanoclusters. We have used scanning tunnelling microscopy (STM), x-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD) to study the adsorption, coadsorption and reaction of CO and O2 on the Au/Ni(111) surface alloy and the clean Ni(111) surface with the goal of clarifying the mechanism or mechanisms behind this interesting phenomenon. In agreement with the work of Lahr and Ceyer we find that molecular oxygen is required to produce CO2 on the surface but our results seem to indicate a different reaction mechanism than the one proposed in their article.
1 Besenbacher, F.; Chorkendorff, I.; Clausen, B. S.; Hammer, B.; Molenbroek, A. M.; Norskov, J. K.; Stensgaard, I., Design of a surface alloy catalyst for steam reforming. Science 1998, 279, (5358), 1913-1915.
2 Vestergaard, E. K.; Vang, R. T.; Knudsen, J.; Pedersen, T. M.; An, T.; Laegsgaard, E.; Stensgaard, I.; Hammer, B.; Besenbacher, F., Adsorbate-induced alloy phase separation: A direct view by high-pressure scanning tunneling microscopy. Physical Review Letters 2005, 95, (12), 126101.
3 Lahr, D. L.; Ceyer, S. T., Catalyzed CO oxidation at 70 K on an extended Au/Ni surface alloy. Journal Of The American Chemical Society 2006, 128, (6), 1800-1801.