• Piccolo, Laurent
• Molinet-Chinaglia, Clément
• Loridant, Stephane

Abstract

<jats:title>Abstract</jats:title><jats:p>The dynamics of Pt/CeO<jats:sub>2</jats:sub> catalysts is a hot topic since its knowledge can be used to (re)generate more active sites for redox reactions, even at low temperature (&lt;500 °C). While numerous works focus on the atomic scale, the spatial extent of Pt surface diffusion is poorly known. In this work, it is evaluated at the powder agglomerate scale using an original methodology combining SEM‐EDX analysis and <jats:italic>in situ</jats:italic> optical/microRaman hyperspectral imaging performed on a Pt/CeO<jats:sub>2</jats:sub>+CeO<jats:sub>2</jats:sub> mechanical mixture. No intergranular diffusion of platinum during redox cycles at 500 °C is revealed by these techniques, in particular by the Raman images of Ce<jats:sup>3+</jats:sup> and peroxo species, which are highly sensitive to the presence of Pt atoms. It strongly suggests that Pt surface diffusion takes place only at the nanometer scale and could be limited by atom trapping on Pt/CeO<jats:sub>2</jats:sub> agglomerates. Our method for investigating diffusion processes at the micrometer scale may be extended to other thermochemical conditions and other materials.</jats:p>

Topics

• impedance spectroscopy
• surface
• scanning electron microscopy
• Platinum
• Energy-dispersive X-ray spectroscopy