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Global optimization and oxygen dissociation on polyicosahedral Ag32Cu6 core-shell cluster for alkaline fuel cells.

Zhang N, Chen FY, Wu XQ - Sci Rep (2015)

Bottom Line: It is demonstrated that the truncated octahedral (TO) Ag32Cu6 core-shell cluster is less stable than the polyicosahedral (pIh) Ag32Cu6 core-shell cluster from the atomistic models and the DFT calculation shows an agreeable result, so the newfound pIh Ag32Cu6 core-shell cluster is further investigated for potential application for O2 dissociation in oxygen reduction reaction (ORR).The activation energy barrier for the O2 dissociation on pIh Ag32Cu6 core-shell cluster is 0.715 eV, where the d-band center is -3.395 eV and the density of states at the Fermi energy level is maximal for the favorable absorption site, indicating that the catalytic activity is attributed to a maximal charge transfer between an oxygen molecule and the pIh Ag32Cu6 core-shell cluster.This work revises the earlier idea that Ag32Cu6 core-shell nanoparticles are not suitable as ORR catalysts and confirms that Ag-Cu nanoalloy is a potential candidate to substitute noble Pt-based catalyst in alkaline fuel cells.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xian 710072, China.

ABSTRACT
The structure of 38 atoms Ag-Cu cluster is studied by using a combination of a genetic algorithm global optimization technique and density functional theory (DFT) calculations. It is demonstrated that the truncated octahedral (TO) Ag32Cu6 core-shell cluster is less stable than the polyicosahedral (pIh) Ag32Cu6 core-shell cluster from the atomistic models and the DFT calculation shows an agreeable result, so the newfound pIh Ag32Cu6 core-shell cluster is further investigated for potential application for O2 dissociation in oxygen reduction reaction (ORR). The activation energy barrier for the O2 dissociation on pIh Ag32Cu6 core-shell cluster is 0.715 eV, where the d-band center is -3.395 eV and the density of states at the Fermi energy level is maximal for the favorable absorption site, indicating that the catalytic activity is attributed to a maximal charge transfer between an oxygen molecule and the pIh Ag32Cu6 core-shell cluster. This work revises the earlier idea that Ag32Cu6 core-shell nanoparticles are not suitable as ORR catalysts and confirms that Ag-Cu nanoalloy is a potential candidate to substitute noble Pt-based catalyst in alkaline fuel cells.

No MeSH data available.


Related in: MedlinePlus

(a) Energy evolution progress plot in GA program for the truncated octahedron Ag38 cluster and the polyicosahedral Ag32Cu6 core-shell cluster. Symbols: ▲ average energy, ■ lowest energy, ● highest energy. (b) Δ1 and Δ2 in binding energy for the 38 atom Ag-Cu cluster system.
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f1: (a) Energy evolution progress plot in GA program for the truncated octahedron Ag38 cluster and the polyicosahedral Ag32Cu6 core-shell cluster. Symbols: ▲ average energy, ■ lowest energy, ● highest energy. (b) Δ1 and Δ2 in binding energy for the 38 atom Ag-Cu cluster system.

Mentions: Evolutionary progress plots during the convergence of the GA on the lowest energy Ag38 and Ag32Cu6 cluster are shown in Fig. 1(a). The figure shows that the GA requires 74 generations to find the lowest energy structure of Ag32Cu6 cluster but only 35 generations to find the lowest energy structure of Ag38 clusters. In both cases, the energy (highest, lowest and average - the average value of its total potential energy for the population) are becoming equal with increasing generation number, indicating that the population converges on a single structure.


Global optimization and oxygen dissociation on polyicosahedral Ag32Cu6 core-shell cluster for alkaline fuel cells.

Zhang N, Chen FY, Wu XQ - Sci Rep (2015)

(a) Energy evolution progress plot in GA program for the truncated octahedron Ag38 cluster and the polyicosahedral Ag32Cu6 core-shell cluster. Symbols: ▲ average energy, ■ lowest energy, ● highest energy. (b) Δ1 and Δ2 in binding energy for the 38 atom Ag-Cu cluster system.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493688&req=5

f1: (a) Energy evolution progress plot in GA program for the truncated octahedron Ag38 cluster and the polyicosahedral Ag32Cu6 core-shell cluster. Symbols: ▲ average energy, ■ lowest energy, ● highest energy. (b) Δ1 and Δ2 in binding energy for the 38 atom Ag-Cu cluster system.
Mentions: Evolutionary progress plots during the convergence of the GA on the lowest energy Ag38 and Ag32Cu6 cluster are shown in Fig. 1(a). The figure shows that the GA requires 74 generations to find the lowest energy structure of Ag32Cu6 cluster but only 35 generations to find the lowest energy structure of Ag38 clusters. In both cases, the energy (highest, lowest and average - the average value of its total potential energy for the population) are becoming equal with increasing generation number, indicating that the population converges on a single structure.

Bottom Line: It is demonstrated that the truncated octahedral (TO) Ag32Cu6 core-shell cluster is less stable than the polyicosahedral (pIh) Ag32Cu6 core-shell cluster from the atomistic models and the DFT calculation shows an agreeable result, so the newfound pIh Ag32Cu6 core-shell cluster is further investigated for potential application for O2 dissociation in oxygen reduction reaction (ORR).The activation energy barrier for the O2 dissociation on pIh Ag32Cu6 core-shell cluster is 0.715 eV, where the d-band center is -3.395 eV and the density of states at the Fermi energy level is maximal for the favorable absorption site, indicating that the catalytic activity is attributed to a maximal charge transfer between an oxygen molecule and the pIh Ag32Cu6 core-shell cluster.This work revises the earlier idea that Ag32Cu6 core-shell nanoparticles are not suitable as ORR catalysts and confirms that Ag-Cu nanoalloy is a potential candidate to substitute noble Pt-based catalyst in alkaline fuel cells.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xian 710072, China.

ABSTRACT
The structure of 38 atoms Ag-Cu cluster is studied by using a combination of a genetic algorithm global optimization technique and density functional theory (DFT) calculations. It is demonstrated that the truncated octahedral (TO) Ag32Cu6 core-shell cluster is less stable than the polyicosahedral (pIh) Ag32Cu6 core-shell cluster from the atomistic models and the DFT calculation shows an agreeable result, so the newfound pIh Ag32Cu6 core-shell cluster is further investigated for potential application for O2 dissociation in oxygen reduction reaction (ORR). The activation energy barrier for the O2 dissociation on pIh Ag32Cu6 core-shell cluster is 0.715 eV, where the d-band center is -3.395 eV and the density of states at the Fermi energy level is maximal for the favorable absorption site, indicating that the catalytic activity is attributed to a maximal charge transfer between an oxygen molecule and the pIh Ag32Cu6 core-shell cluster. This work revises the earlier idea that Ag32Cu6 core-shell nanoparticles are not suitable as ORR catalysts and confirms that Ag-Cu nanoalloy is a potential candidate to substitute noble Pt-based catalyst in alkaline fuel cells.

No MeSH data available.


Related in: MedlinePlus