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 SiO2, ZrO2, and TiO2 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. PtO2 species are formed on all supports investigated after O2-plasma exposure. A two-step thermal decomposition (PtO2 → 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 ZrO2 under annealing treatments in O2. Strong NP/support interactions and the formation of Pt−Ti−O alloys are detected for Pt/TiO2 up...
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