In situ scanning tunneling microscopy studies of bimetallic cluster growth: Pt-Rh on TiO2(110)

COLL 180

J. B. Park, park@mail.chem.sc.edu, J. S. Ratliff, ratliff@mail.chem.sc.edu, and D. A. Chen, chen@mail.chem.sc.edu. Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208
The growth of Pt-Rh bimetallic nanoclusters, formed by depositing Pt on 0.3ML of Rh predeposited on a TiO2(110) surface, has been investigated using scanning tunneling microscopy (STM) and low energy ion scattering (LEIS). In situ STM studies during Pt deposition show that bimetallic nanoclusters are produced by direct incorporation of Pt atoms into existing Rh clusters or coalescence of nucleated Pt clusters with predeposited Rh clusters. Cluster densities for Pt-Rh growth are lower than those for pure Pt growth, suggesting that the Rh clusters act as nuclei (seed clusters) for the formation of Pt-Rh bimetallic clusters. In situ STM studies at 100K and 450K clarify the Pt-Rh growth kinetics based on the different adatom diffusion rates. LEIS experiments show that Pt does not completely cover the surfaces of the Rh clusters even at the highest Pt coverage, suggesting that Rh atoms can diffuse within the Pt-Rh bimetallic nanoclusters.
 

Fundamental Research in Colloid and Surface Chemistry
6:00 PM-8:00 PM, Monday, 27 March 2006 OMNI at CNN Center -- Grand Blrm D, Poster

Division of Colloid and Surface Chemistry

The 231st ACS National Meeting, Atlanta, GA, March 26-30, 2006