Regensburg 2022 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 70: Supported nanoclusters: Structure, Reactions, Catalysis
O 70.2: Vortrag
Donnerstag, 8. September 2022, 15:30–15:45, H6
The role of water in oxidation of the Pt/Co3O4 interface — •Yaroslava Lykhach1, Lukáš Fusek1,2, Maximilian Kastenmeier1, Tomáš Skála2, Nataliya Tsud2, Viktor Johánek2, Sascha Mehl3, Josef Mysliveček2, Olaf Brummel1, and Jörg Libuda1 — 1Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany — 2Charles University, Prague, Czech Republic — 3Elettra-Sincrotrone Trieste SCpA, Basovizza-Trieste, Italy
Electronic metal-oxide interactions (EMSI) play a major role in the design of advanced functional materials for applications in catalysis. We investigated the influence of the EMSI on the oxidation state of ultra-small Pt particles supported on a well-ordered Co3O4(111) substrate in the presence of co-adsorbates, i.e. hydroxyl groups and molecularly adsorbed water, by means of synchrotron radiation photoelectron spectroscopy and scanning tunnelling microscopy. The EMSI gives rise to charge transfer across the metal-oxide interface and results in partial oxidation of Pt deposits coupled with partial reduction of Co3O4(111). We detected ultra-small Ptδ+ aggregates in combination with atomically dispersed Pt2+/4+ species. While the oxidation degree of Pt deposits is not influenced by the presence of co-adsorbates, the magnitude of the charge transfer is enhanced in the presence of molecularly adsorbed water. Subsequent annealing in UHV leads to re-oxidation of Co3O4(111) accompanied by an increase in the amount of Pt4+ species. This observation suggests the re-dispersion of Ptδ+ aggregates to Pt4+ species triggered by the dissociation of water.