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Multiscale Sampling of a Heterogeneous Water/Metal Catalyst Interface using Density Functional Theory and Force-Field Molecular Dynamics
Published on: April 12, 2019
Size-dependent subnanometer Pd cluster (Pd4, Pd6, and Pd17) water oxidation electrocatalysis
Gihan Kwon1, Glen A Ferguson, Christopher J Heard
1Materials Science Division,Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA.
ACS Nano
|June 27, 2013
Summary
Size-selected palladium clusters on ultrananocrystalline diamond electrodes reveal catalytic activity for water oxidation. Smaller clusters (Pd6, Pd17) show high activity, unlike Pd4, suggesting specific structural sites are crucial for efficient oxygen evolution.
Area of Science:
- Catalysis
- Materials Science
- Electrochemistry
Background:
- Water oxidation is vital for electrical fuel generation, with catalysis playing a key role.
- Understanding catalytic sites is crucial for improving electrocatalysts for electrolysis and solar fuel applications.
- Palladium (Pd) clusters are investigated for their potential in water oxidation catalysis.
Purpose of the Study:
- To investigate the relationship between the size of palladium (Pd) clusters and their activity in water oxidation.
- To probe the role of specific structural features, such as bridging Pd-Pd sites, in catalytic performance.
- To evaluate the suitability of ultrananocrystalline diamond (UNCD) as a stable electrode material for water oxidation studies.
Main Methods:
- Synthesis of size-selected palladium clusters (Pd4, Pd6, Pd17).
- Deposition of Pd clusters onto ultrananocrystalline diamond (UNCD) coated silicon electrodes.
- Electrochemical measurements in alkaline conditions to assess water oxidation activity.
- Theoretical calculations to elucidate the mechanism of catalysis.
- Synchrotron studies to analyze electrode and cluster stability.
Main Results:
- Pd4 clusters exhibited no water oxidation activity.
- Pd6 and Pd17 clusters demonstrated high catalytic activity (turnover rate per Pd atom) for water oxidation.
- Theoretical calculations suggest bridging Pd-Pd sites in 3D clusters are key for oxygen evolution.
- The UNCD electrode material proved stable under harsh experimental conditions.
- The Pd/UNCD system showed stable electrochemical potentials over multiple cycles.
Conclusions:
- Palladium cluster size significantly impacts water oxidation catalytic activity.
- Bridging Pd-Pd sites, present in larger, 3D clusters, are likely the active sites for oxygen evolution.
- UNCD is a highly stable and effective electrode support for studying water oxidation catalysts.
- This study provides a direct experimental comparison to theoretical models of catalytic activity.
