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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) HRTEM image of Ag-Cu nanoalloy via PLD, (b) Atomic model for 561-atom Ag-Cu cluster, (c) ORR polarization curves for Ag-Cu nanoalloy (d) Koutecky Levich plots collected from the ORR for Ag-Cu nanoalloy.
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f5: (a) HRTEM image of Ag-Cu nanoalloy via PLD, (b) Atomic model for 561-atom Ag-Cu cluster, (c) ORR polarization curves for Ag-Cu nanoalloy (d) Koutecky Levich plots collected from the ORR for Ag-Cu nanoalloy.

Mentions: To verify the theoretical prediction above, we synthesis the Ag-Cu nanoalloy in a home-made pulse laser deposition equipment. Figure 5(a) shows that these nanoparticles are 1–5 nm in diameter with an average size of 2.58 nm in the amorphous films. Figure S3(a) shows a typical Ag-Cu nanoparticle with size of 2.6 nm outlined by a red rectangle, its Fast Fourier Transform (FFT) image in the Figure S3(b) clearly illustrates the characteristic of core-shell structure, as indicated by two set of aligned diffraction spots corresponding to Cu and Ag phase with cube on cube epitaxial relationship. Moreover, the inverse of Fast Fourier Transform (IFFT) image in the Figure S3(c) clearly shows the location of Ag and Cu fringes is Cu core and Ag shell. As shown in Figure S4, the Ag-Cu core-shell cluster possesses an atomic ratio of Ag to Cu is 80:20.


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) HRTEM image of Ag-Cu nanoalloy via PLD, (b) Atomic model for 561-atom Ag-Cu cluster, (c) ORR polarization curves for Ag-Cu nanoalloy (d) Koutecky Levich plots collected from the ORR for Ag-Cu nanoalloy.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f5: (a) HRTEM image of Ag-Cu nanoalloy via PLD, (b) Atomic model for 561-atom Ag-Cu cluster, (c) ORR polarization curves for Ag-Cu nanoalloy (d) Koutecky Levich plots collected from the ORR for Ag-Cu nanoalloy.
Mentions: To verify the theoretical prediction above, we synthesis the Ag-Cu nanoalloy in a home-made pulse laser deposition equipment. Figure 5(a) shows that these nanoparticles are 1–5 nm in diameter with an average size of 2.58 nm in the amorphous films. Figure S3(a) shows a typical Ag-Cu nanoparticle with size of 2.6 nm outlined by a red rectangle, its Fast Fourier Transform (FFT) image in the Figure S3(b) clearly illustrates the characteristic of core-shell structure, as indicated by two set of aligned diffraction spots corresponding to Cu and Ag phase with cube on cube epitaxial relationship. Moreover, the inverse of Fast Fourier Transform (IFFT) image in the Figure S3(c) clearly shows the location of Ag and Cu fringes is Cu core and Ag shell. As shown in Figure S4, the Ag-Cu core-shell cluster possesses an atomic ratio of Ag to Cu is 80:20.

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