Parts | Days | Selection | Search | Downloads | Help
O: Oberflächenphysik
O 33: Teilchen und Cluster II
O 33.5: Talk
Monday, March 7, 2005, 11:45–12:00, TU EB107
Preparation and characterization of fully oxidized TiO2 films on Ru (0001) and of Au/TiO2/Ru(0001) model catalysts — •zhong zhao, T. Diemant, H. Rauscher, and R.J. Behm — Abt.Oberflächenchemie und Katalyse, Universität Ulm, 89069, Ulm
As part of an effort to study CO oxidation on Au/TiO2 model catalyst, we investigated the growth, structure and chemical composition of completely oxidized TiO2 films (thickness ca. 10 monolayers (ML)) on a Ru(0001) substrate, and Au/TiO2 model catalysts prepared by Au evaporation on these films (catalytic properties of these model systems see [1]). Atomic resolution STM images show that after Ti deposition in O2 (640 K) and annealing in O2 , the TiOx film is closed, relatively flat, and consists of TiO2 (110). Upon room temperature Au evaporation and at lower Au coverages (≤0.2) ML Au nanoparticles nucleate preferentially at steps, a small fraction of them nucleates at defect sites on the TiO2 terraces. With higher Au coverages, the Au particles grow increasingly on the whole surface. UHV annealing at 770 K (10 min) causes the Au clusters to grow, but different from Pt/TiO2 [2] we find no encapsulation by TiO2. The stability of the Au nanoparticles is discussed, comparing with recent findings for Au/TiO2 (110) model catalysts [3]. [1] T. Diemant, Z. Zhao, H. Rauscher, and R.J. Behm, DPG Spring Meeting, AKF Surface Physics, Berlin (2005) [2] O. Dulub, W. Hebenstreit, and U. Diebold, Phys. Rev. Lett. 84, 3646 (2000) [3] S. Kielbassa, M. Kinne, and R.J. Behm, J. Phys. Chem. B, in press