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Oxidation induced restructuring of Rh-Ga SCALMS model catalyst systems
Haiko Wittkämper1, Sven Maisel2, Mingjian Wu3
1Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Lehrstuhl für Physikalische Chemie II, Egerlandstr. 3, 91058 Erlangen, Germany.
The Journal of Chemical Physics
|September 16, 2020
Summary
Supported rhodium-gallium (Rh-Ga) catalysts form a protective gallium oxide shell upon oxidation. This shell enriches Rh, enhancing catalytic activity and stability for advanced applications.
Area of Science:
- Materials Science
- Surface Chemistry
- Catalysis
Background:
- Supported liquid metal solutions are emerging as promising catalysts.
- Rhodium-gallium (Rh-Ga) alloys show potential for catalytic applications.
- Understanding alloy oxidation is crucial for catalyst stability and performance.
Purpose of the Study:
- To investigate the oxidation behavior of Rh-Ga alloy droplets and nanoparticles.
- To elucidate the mechanism of Rh incorporation into gallium oxide shells.
- To correlate structural changes with catalytic properties.
Main Methods:
- X-ray photoelectron spectroscopy (XPS) under various pressure conditions.
- Transmission electron microscopy (TEM) for structural analysis.
- Ab initio molecular dynamics and computational modeling.
Main Results:
- Oxidation of Rh-Ga alloys forms a Rh-enriched gallium oxide shell.
- TEM confirmed a ~4 nm thick gallium oxide film containing Rh on nanoparticles.
- Computational studies revealed Rh substitutes Ga in the Ga2O3 lattice.
Conclusions:
- Rh-Ga catalysts form a protective, Rh-enriched oxide shell during oxidation.
- This shell structure is key to the stability and potential activity of these catalysts.
- Rh incorporation occurs via substitution in the gallium oxide structure.
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