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Catalytic Reactions on Pd-Au Bimetallic Model Catalysts
Sungmin Han1, C Buddie Mullins1,2,3
1Department of Chemistry, University of Texas at Austin, Austin, Texas 78712-0231, United States.
Accounts of Chemical Research
|December 29, 2020
Summary
This study uses ultrahigh vacuum (UHV) surface science to investigate palladium-gold (Pd-Au) model catalysts. Findings reveal how Pd ensemble size influences hydrogen (H2) and oxygen (O2) reactions, crucial for catalysis.
Area of Science:
- Surface Science
- Heterogeneous Catalysis
- Materials Science
Background:
- Palladium-gold (Pd-Au) catalysts exhibit enhanced activity due to ensemble effects.
- Ultrahigh vacuum (UHV) surface science enables molecular-level study of catalytic reactions.
- Understanding simple molecule interactions (H2, O2, CO) on Pd-Au is vital for catalysis.
Purpose of the Study:
- To investigate the role of Pd ensemble size on Pd-Au model catalysts.
- To elucidate the reaction mechanisms of H2, O2, and organic molecules on Pd-Au surfaces.
- To apply UHV surface science techniques to understand catalytic processes.
Main Methods:
- Utilized UHV methods to study Pd-Au planar model catalysts.
- Employed H2 as a probe molecule to quantify surface composition based on desorption temperatures.
- Analyzed O2 activation and reaction pathways under controlled UHV conditions.
Main Results:
- H2 adsorption and desorption behavior are sensitive to Pd ensemble size, distinguishing interface sites from bulk Pd.
- Pd-Au interfaces are key reaction sites for H2 generation from formic acid and ethanol with reduced decomposition.
- O2 activation on Pd clusters yields reactive O adatoms, with enhanced reactivity at Pd-Au interfaces, facilitating CO and organic molecule oxidation.
Conclusions:
- Pd-Au model catalysts under UHV reveal molecular-level mechanistic details of H and O adatom interactions.
- The findings are applicable to various catalytic processes, including heterogeneous, electro-, and photochemical catalysis.
- Pd ensemble size critically controls catalytic activity and selectivity on Pd-Au surfaces.
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