AVS 49th International Symposium
    Surface Science Wednesday Sessions
       Session SS-WeP

Paper SS-WeP5
Surface Characterization of Dendrimer-Encapsulated Pt Nanoparticles

Wednesday, November 6, 2002, 11:00 am, Room Exhibit Hall B2

Session: Surface Science Poster Session
Presenter: B.T. Long, University of South Carolina
Authors: B.T. Long, University of South Carolina
F. Parsons, University of South Carolina
J. Gao, University of South Carolina
C. Murphy, University of South Carolina
D.A. Chen, University of South Carolina
Correspondent: Click to Email
The ability to prepare metal nanoparticles with narrow size distributions has many potential applications in the field of heterogeneous catalysis. Platinum nanoparticles with uniform size distributions can be prepared from solution in the presence of poly(amidoamine) generation 4 starburst dendrimers. The resulting Pt nanoparticles have diameters of ~1.5 nm and are encapsulated by the dendrimers. These dendrimer-encapsulated metal nanoparticles have been spin-coated on mica and Au surfaces and imaged by tapping mode AFM and STM. At higher concentrations, the surface is covered by a single-layer dendrimer film while at lower concentrations, dendrimer aggregates are observed. Our goal is to remove the dendrimers from the Pt particles, which can then be used for catalytic studies. Thermal gravimetric analysis experiments have shown that the dendrimer begins to decompose at approximately 200°C, but decomposition is not complete at temperatures below 400°C. Ultrahigh vacuum studies will be used to further address the decomposition of the dendrimers. Specifically, the species that remain on the surface at various stages of dendrimer decomposition will be characterized by X-ray photoelectron spectroscopy. Gaseous products that desorb from the surface during decomposition will be monitored by temperature programmed desorption.