Title

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

Authors

Authors

L. K. Ono; B. Yuan; H. Heinrich;B. R. Cuenya

Comments

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Abbreviated Journal Title

J. Phys. Chem. C

Keywords

RAY PHOTOELECTRON-SPECTROSCOPY; RESOLUTION ELECTRON-MICROSCOPY; SINGLE-CRYSTAL SURFACES; THIN-FILMS; CATALYTIC-PROPERTIES; ZRO2 FILMS; MICELLE ENCAPSULATION; GOLD NANOPARTICLES; SUBSURFACE OXYGEN; CO; OXIDATION; Chemistry, Physical; Nanoscience & Nanotechnology; Materials Science, ; Multidisciplinary

Abstract

This article presents a systematic study of the formation and thermal stability of Pt oxide species on size-Selected Pt nanoparticles (NPs) supported on SiO(2), ZrO(2), and TiO(2) thin films. The studies were carried Out in ultrahigh vacuum (UHV) by temperature-dependent X-ray photoelectron spectroscopy (XPS) measurements and ex situ transmission electron microscopy and atomic force microscopy. The NPs were synthesized by inverse micelle encapsulation and oxidized in UHV at room temperature by an oxygen plasma treatment. For a given particle size distribution, the role played by the NP support on the stability of Pt oxides was analyzed. PtO(2) species are formed on all supports investigated after O(2)-plasma exposure. A two-step thermal decomposition (PtO(2) -> PtO -> Pt) is observed from 300 to 600 K upon annealing in UHV. The stability of oxidized Pt species was found to be enhanced on ZrO(2) under annealing treatments in O(2). Strong NP/support interactions and the formation of Pt-Ti-O alloys are detected for Pt/TiO(2) upon annealing in UHV above 550 K but not under an identical treatment in O(2). Furthermore, thermal treatments in both environments above 700 K lead to the encapsulation of Pt by TiO(x). The final shape of the micellar Pt NPs is influenced by the type of underlying support as well as by the post-deposition treatment. Spherical Pt NPs are stable on SiO(2), ZrO(2), and TiO(2) after in situ ligand removal with atomic oxygen at RT. However, annealing in UHV at 1000 K leads to NP flattening on ZrO(2) and to the diffusion of Pt NPs into TiO(2). The stronger the nature of the NP/support interaction, the more dramatic is the change in the NP shape (TiO(2) > ZrO(2) > SiO(2)).

Journal Title

Journal of Physical Chemistry C

Volume

114

Issue/Number

50

Publication Date

1-1-2010

Document Type

Article

Language

English

First Page

22119

Last Page

22133

WOS Identifier

WOS:000285236800033

ISSN

1932-7447

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