AVS 57th International Symposium & Exhibition
    Surface Science Monday Sessions
       Session SS1-MoA

Paper SS1-MoA2
Formation and Thermal Stability of Platinum Oxides on Size-Selected Platinum Nanoparticles: Support Effects

Monday, October 18, 2010, 2:20 pm, Room Picuris

Session: Nanocluster Reactivity
Presenter: L.K. Ono, University of Central Florida
Authors: L.K. Ono, University of Central Florida
J.R. Croy, University of Central Florida
H. Heinrich, University of Central Florida
B. Roldan Cuenya, University of Central Florida
Correspondent: Click to Email
Metal-loaded diblock-copolymer micelles have been used to synthesize size-selected self-assembled Pt nanoparticles (NPs). Ex-situ atomic force microscopy (AFM) and transmission electron microscopy (TEM) as well as in-situ X-ray photoelectron spectroscopy (XPS) measurements were performed to investigate the formation and thermal stability of PtOx species on Pt NPs supported on SiO2, ZrO2, and TiO2 thin films. For a given particle size distribution, the role played by the NP support on the stability of Pt oxides was studied. Our findings are: (i) the formation of PtO2 species upon atomic oxygen exposure and a two-step thermal decomposition process (PtO2 -> PtO -> Pt) from 300 K to 600 K upon annealing in vacuum; (ii) the enhanced stability of PtOx species on ZrO2 as compared to SiO2 and TiO2 upon annealing in O2, and in vacuum, possibly due to its stabilization at the NP/support interface; (iii) the onset of strong NP/support interactions above 600 K and the formation of Pt-Ti and/or Pt-Ti-O alloys for the Pt-NP/TiO2 system associated with the creation of O-vacancies on TiO2 upon annealing in vacuum, leading to the encapsulation of Pt by TiOx above 700 K.

The size-dependent stability of PtOx species in Pt NPs supported on SiO2 as compared to bulk Pt(111) will be demonstrated based on temperature programmed desorption measurements.