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Surface-Structure Libraries: Multifrequential Oscillations in Catalytic Hydrogen Oxidation on Rhodium
Yuri Suchorski1, Martin Datler1, Ivan Bespalov1
1Institute of Materials Chemistry, Technische Universität Wien, Getreidemarkt 9, 1060 Vienna, Austria.
Catalytic hydrogen oxidation on rhodium surfaces exhibits complex, multifrequential oscillating patterns. These chemical waves change frequency across different crystal domains, revealing unique surface dynamics.
Area of Science:
- Surface science
- Heterogeneous catalysis
- Chemical kinetics
Background:
- Catalytic hydrogen oxidation on rhodium is a key reaction in many chemical processes.
- Understanding surface dynamics and reaction patterns is crucial for catalyst design and efficiency.
- Previous studies have not fully elucidated the complex spatiotemporal behaviors observed under specific conditions.
Purpose of the Study:
- To investigate multifrequential oscillating spatiotemporal patterns during catalytic hydrogen oxidation on rhodium.
- To analyze the influence of crystallographic domains on reaction dynamics.
- To elucidate the role of subsurface oxygen in kinetic oscillations.
Main Methods:
- In situ observation using photoemission electron microscopy (PEEM) at 10⁻⁶ mbar pressure.
- Analysis of chemical wave propagation and frequency changes across Rh(hkl) domains.
- Microkinetic modeling to rationalize experimental observations and kinetic parameters.
Main Results:
- Observation of periodic chemical waves with varying oscillation frequencies across different Rh(hkl) domains.
- Identification of crystallographically specific μm-sized domains exhibiting individual wave patterns.
- Evidence for subsurface oxygen formation facilitated by stepped surfaces, acting as a kinetic oscillation feedback mechanism.
- In situ observation of subsurface oxygen network formation from colliding reaction fronts.
Conclusions:
- The study reveals a structure library of reaction dynamics on polycrystalline rhodium surfaces.
- Subsurface oxygen formation is identified as a key feedback mechanism driving kinetic oscillations.
- Microkinetic modeling successfully rationalizes the observed oscillations and their dependence on surface structure and reaction conditions.
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