| AVS 54th International Symposium | |
| Surface Science | Monday Sessions |
| Session SS1-MoM |
| Session: | Catalysis on Clusters and Nanoparticles |
| Presenter: | J. Matthiesen, University of Aarhus, Denmark |
| Authors: | S. Wendt, University of Aarhus, Denmark J. Matthiesen, University of Aarhus, Denmark D. Matthey, University of Aarhus, Denmark J.G. Wang, University of Aarhus, Denmark R. Schaub, University of Aarhus, Denmark E. Lægsgaard, University of Aarhus, Denmark B. Hammer, University of Aarhus, Denmark F. Besenbacher, University of Aarhus, Denmark |
| Correspondent: | Click to Email |
Finding of distinctive catalytic properties of dispersed gold nanoparticles on oxide supports has stimulated extensive research activities, and a general consensus now exists on several aspects of this system. The size of the gold particles significantly affects the catalytic activity, and the gold clusters must be smaller than 5 nm for high catalytic activity.1,2 The choice of the oxide support influences the catalytic activity, so there is a strong ‘support effect’ in addition to the ‘size effect’.1 However, the relation of the adhesion properties of nanosized gold with catalytic activity is still unresolved. We studied the nucleation of gold clusters on TiO2(110) surfaces in three different oxidation states by high-resolution scanning tunneling microscopy (STM). The three TiO2(110) supports chosen were (i) reduced having bridging oxygen vacancies, (ii) hydrated having bridging hydroxyl groups, and (iii) oxidized having oxygen ad-atoms.3 At room temperature gold clusters nucleate homogeneously on the terraces of the reduced and oxidized supports, while on the hydrated TiO2(110) surface clusters form preferentially at the step edges. From interplay with density functional theory (DFT) calculations, we identified two different gold - TiO2(110) adhesion mechanisms for the reduced and oxidized supports. The adhesion of gold clusters is strongest on the oxidized support, and the implications of this finding for catalytic applications are discussed.4
1Meyer, R., Lemire, C., Shaikhutdinov, Sh.K., Freund, H.-J., Gold Bulletin 37 (2004) 72-124.
2Valden, M., Lai, X., Luo, K., Guo, Q., Goodman, D.W., Science 281 (1998) 1647-1650.
3Wendt, S., Schaub, R., Matthiesen, J., Vestergaard, E.K., Wahlström, E., Rasmussen, M.D., Thostrup, P., Molina, L.M., Lægsgaard, E., Stensgaard, I., Hammer, B., Besenbacher, F., Surf. Sci. 598 (2005) 226-245.
4Matthey, D., Wang, J. G., Wendt, S., Matthiesen, J., Schaub, R., Lægsgaard, E., Hammer, B., Besenbacher, F., Science 315 (2007) 1692 - 1696.