Equilibrium and stability of phase-separating Au–Pt nanoparticles

Braidy, Nadi; Purdy, G.R.; Botton, Gianluigi A.

doi:10.1016/j.actamat.2008.08.024

Cited by 70 publications

(81 citation statements)

References 41 publications

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“…Different configurations have been reported experimentally, though some may be meta-stable. Mixed (Mihut et al 2002;Luo et al 2005), Pt core Au shell (Abrams et al 2009;Selvarani et al 2009) and Au core Pt shell (Braidy et al 2008;Yancey et al 2010) configurations have been reported by different groups. In a remarkable experiment (Braidy et al 2008), the Au core Pt shell configuration was maintained when the bimetallic cluster was thermally annealed at 300…”

Section: Introductionmentioning

confidence: 99%

“…One contribution of 16 to a Special feature 'High-performance computing in the chemistry and physics of materials '. In experimental studies of bimetallic clusters, Pt-Au is among the most popular systems owing to its promising catalytic capacities (Pearson 1972;Okamoto & Massalski 1985;Mihut et al 2002;Luo et al 2005;Bond et al 2006;Hernández-Fernández et al 2007;Braidy et al 2008;Ferrando et al 2008a;Zhang et al 2008;Abrams et al 2009;Peng & Yang 2009;Selvarani et al 2009;Yancey et al 2010). Bimetallic Pt-Au clusters have a wide range of catalytic applications, including oxygen reduction in fuel cells (Hernández-Fernández et al 2007), methanol and formic acid oxidations (Zhang et al 2008;Peng & Yang 2009) and selective oxidations (Bond et al 2006).…”

Section: Introductionmentioning

confidence: 99%

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Study of 40-atom Pt–Au clusters using a combined empirical potential-density functional approach

Tran

Johnston

2011

Proc. R. Soc. A.

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This work is a theoretical study of 40-atom Pt-Au clusters which are of interest owing to the electronic shell closure of 40-atom noble metal clusters and the current focus on bimetallic Pt-Au clusters as catalysts. The methodology is a complementary combination of a genetic algorithm search for an empirical potential and density functional theory (DFT) reoptimization. Structures based on truncated-octahedral, icosahedral, decahedral and fivefold pancake geometries are found to be energetically favoured for different composition regions at the empirical-potential level and this is partially confirmed at the DFT level. The large HOMO-LUMO gaps found for the icosahedral and fivefold pancake structures indicate electronic shell closure effects, while the truncated-octahedral and decahedral structures have small gaps. The DFT calculations confirm that, for Pt 20 Au 20 truncated-octahedral structures, the Pt core Au shell configuration which has two Au atoms capping the (100) facets is most energetically favoured, and the layered (phase segregated) configuration also has lower energy compared with the Au core Pt shell and mixed configurations.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Study of 40-atom Pt–Au clusters using a combined empirical potential-density functional approach

Tran

Johnston

2011

Proc. R. Soc. A.

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“…47 Pt−Au NPs show physical properties different from their bulk counterparts. 41 Pt−Au single-phase alloys, partial alloys, hetero aggregates, and core−shell NPs can be prepared. 31,42−45 The alloy structure of Pt−Au NPs supported by silica can be preserved at 700°C.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen Adsorption on Platinum–Gold Bimetallic Nanoparticles: A Density Functional Theory Study

Linder

Nardelli

et al. 2013

J. Phys. Chem. C

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Using ab initio density functional theory, we investigate how hydrogen interacts with Pt−Au bimetallic nanoparticles (NPs) of various compositions. Several Au, Pt, and Pt−Au NPs of 85 atoms are considered. The results indicate that both the adsorption energy and the geometry of the most favorable adsorption sites are dependent on the local distribution of metal atoms. On some adsorption sites, our results suggest that the hydrogen adsorption on Pt−Au NPs can be more favorable than that on monometallic Pt NPs of similar size. The results are interpreted with the aid of a number of electronic structure details, including d-band structure, density of states, electronic population, and charge density differences.

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“…A relatively small number of papers have been devoted to nanoscale phase equilibria of two-component systems [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. For binary and multi-component solutions, the configurational entropy is one of the basic terms of the Gibbs energy of the solution phases, and thus its precise knowledge is crucial for nano-equilibrium calculations.…”

Section: Introductionmentioning

confidence: 99%

On the Configurational Entropy of Nanoscale Solutions for More Accurate Surface and Bulk Nano-Thermodynamic Calculations

Dezso

Kaptay

2017

Entropy

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Abstract:The configurational entropy of nanoscale solutions is discussed in this paper. As follows from the comparison of the exact equation of Boltzmann and its Stirling approximation (widely used for both macroscale and nanoscale solutions today), the latter significantly over-estimates the former for nano-phases and surface regions. On the other hand, the exact Boltzmann equation cannot be used for practical calculations, as it requires the calculation of the factorial of the number of atoms in a phase, and those factorials are such large numbers that they cannot be handled by commonly used computer codes. Herewith, a correction term is introduced in this paper to replace the Stirling approximation by the so-called "de Moivre approximation". This new approximation is a continuous function of the number of atoms/molecules and the composition of the nano-solution. This correction becomes negligible for phases larger than 15 nm in diameter. However, the correction term does not cause mathematical difficulties, even if it is used for macro-phases. Using this correction, future nano-thermodynamic calculations will become more precise. Equations are worked out for both integral and partial configurational entropies of multi-component nano-solutions. The equations are correct only for nano-solutions, which contain at least a single atom of each component (below this concentration, there is no sense to make any calculations).

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Equilibrium and stability of phase-separating Au–Pt nanoparticles

Cited by 70 publications

References 41 publications

Study of 40-atom Pt–Au clusters using a combined empirical potential-density functional approach

Study of 40-atom Pt–Au clusters using a combined empirical potential-density functional approach

Hydrogen Adsorption on Platinum–Gold Bimetallic Nanoparticles: A Density Functional Theory Study

On the Configurational Entropy of Nanoscale Solutions for More Accurate Surface and Bulk Nano-Thermodynamic Calculations

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