| AVS 59th Annual International Symposium and Exhibition | |
| Surface Science | Wednesday Sessions |
| Session SS-WeA |
| Session: | Catalysis on Metals and Alloys |
| Presenter: | D.A. Chen, University of South Carolina |
| Authors: | R.P. Galhenage, University of South Carolina H. Yan, University of South Carolina A. Duke, University of South Carolina K. Xie, University of South Carolina D.A. Chen, University of South Carolina |
| Correspondent: | Click to Email |
The nucleation, growth and surface composition of bimetallic clusters on titania have been investigated as model systems for understanding how surface chemistry can be controlled by bimetallic composition and interactions between the clusters and the oxide support. Specifically, we have focused on Au-based bimetallic systems (Au-Pt, Au-Ni, Au-Co) as well as Co-Pt systems. Scanning tunneling microscopy studies demonstrate that bimetallic clusters can be formed via sequential deposition when there is a difference in mobility between the two metals; the more mobile atoms (i.e. Au) can be nucleated at existing Ni, Pt and Co clusters. The surfaces of the Au-containing bimetallic clusters are almost pure Au at Au compositions greater than 50% due to the lower surface free energy of Au compared to other metals. In contrast, the Co-Pt clusters are rich in Pt despite the lower surface energy of Co. In the Au-containing bimetallic clusters, CO and methanol adsorbates induce diffusion of Pt and Ni to surface, whereas this effect is not observed for CO on Au-Co. The activity of these model surfaces have been studied in a prototype recirculating loop microreactor.