Zinc coverage dependent structure of PdZn surface alloy.
Xiang He1, Yucheng Huang, Zhao-Xu Chen
1Institute of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Key Laboratory of Mesoscopic Chemistry of MOE, Nanjing University, China.
Physical Chemistry Chemical Physics : PCCP
|November 18, 2010
Summary
Zinc (Zn) coverage on palladium (Pd(111)) surfaces dictates surface alloy formation. Low Zn coverage creates small palladium ensembles, explaining formaldehyde desorption peaks observed in experiments.
Area of Science:
- Surface science
- Materials science
- Computational chemistry
Background:
- Catalytic performance is highly dependent on the surface structure and composition of alloys.
- Understanding surface alloy formation is crucial for designing efficient catalysts.
Purpose of the Study:
- To investigate the surface structure of palladium (Pd(111)) with varying zinc (Zn) coverages using Monte Carlo simulations.
- To correlate surface alloy structures with experimental observations of formaldehyde desorption.
Main Methods:
- Monte Carlo simulations were employed to model the surface structure of Pd(111) with different Zn coverages.
- Simulated surface alloy compositions were analyzed as a function of Zn deposition.
Main Results:
- The composition of the PdZn surface alloy is directly dependent on Zn coverage.
- At high Zn coverage (one or multi-layer), a multilayer 1:1 PdZn surface alloy is formed.
- At submonolayer Zn coverage, palladium-dominated surface alloy islands form, and at very low coverage, small palladium ensembles (3-5 atoms) are prevalent.
Conclusions:
- The formation of PdZn surface alloys is controllable by adjusting Zn coverage.
- The presence of small palladium ensembles at low Zn coverage provides a plausible explanation for the experimentally observed high-temperature formaldehyde desorption peak.
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