| AVS 54th International Symposium | |
| Surface Science | Monday Sessions |
| Session SS1-MoM |
| Session: | Catalysis on Clusters and Nanoparticles |
| Presenter: | J.B. Park, University of South Carolina |
| Authors: | J.B. Park, University of South Carolina D.A. Chen, University of South Carolina |
| Correspondent: | Click to Email |
Gold (Au) nanoclusters deposited on TiO2 supports have been shown to be excellent catalysts for various oxidation reactions such as propylene epoxidation and CO oxidation. The size of the nanoclusters is known to be the most critical factor for their unique catalytic activity. However, Au nanoclusters sinter rapidly at elevated temperature, losing their catalytic activity. In this study, we have investigated how the rate of sintering can be controlled by adding Pt to Au nanoclusters since pure Pt nanoclusters are less sintered than pure Au due to stronger metal-metal bonds. As a model system, Pt and Au nanoclusters were deposited on a single crystal TiO2(110) substrate and investigated by STM, XPS, LEIS, and TPD in UHV. When Au is deposited on Pt clusters, Pt nanoclusters act as seeds for Au nucleation. However, for Pt deposition on Au, the Au clusters do not nucleate the growth of bimetallic Au-Pt clusters. The extent of cluster sintering at 1000K decreases with increasing Pt composition within the clusters. Intermixing of Au and Pt occurs readily at room temperature; for bimetallic Au-Pt clusters prepared by depositing Au on Pt, the surface contains a significant fraction of Pt atoms, despite immiscibility of Au and Pt and lower surface free energy of Au.