Berlin 2024 – scientific programme
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O: Fachverband Oberflächenphysik
O 33: Poster: Supported Nanoclusters and Catalysis
O 33.5: Poster
Tuesday, March 19, 2024, 18:00–20:00, Poster C
In situ observation of Pt encapsulation in powder and single crystalline model catalysts — •Mohammad Salehi1, Florian Kraushofer1, Sebastian Kaiser1, Matthias Krinninger1, Johanna Reich1, Virginia Pérez-Dieste2, Friedrich Esch1, and Barbara A. J. Lechner1 — 1Technical University of Munich, Garching, Germany — 2ALBA Synchrotron Light Source, Barcelona, Spain
The activity of catalysts supported on reducible oxides is frequently altered significantly at high temperatures due to the strong metal support interaction (SMSI), which leads to an encapsulation layer surrounding the noble metal particles, changing the available active sites. Nevertheless, the effects of oxidizing and reducing treatments on the encapsulation layer under high pressures remain controversial, as ultrahigh vacuum (UHV) analyses often fail to fully understand the intricate nature of these systems. To comprehensively apprehend the atomic-scale structural dynamics and the process of active site formation, it is imperative to employ in situ or operando measurements. In this study, we utilize near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) and near-edge X-ray absorption fine structure (NEXAFS) techniques to conduct a comparative analysis between rutile TiO2 powder catalysts and rutile TiO2(110) single crystal samples concerning Pt encapsulation in oxygen. We find that on single crystals, Pt encapsulation dynamics depend both on the reduction state of the sample and on the Pt loading. Powder samples behave more similarly to near-stoichiometric crystals than strongly reduced ones but also show qualitative distinctions
Keywords: SMSI; Pt nanoparticles; encapsulation; NAP-XPS