Ab Initio Study of Stability and Site-Specific Oxygen Adsorption Energies of Pt Nanoparticles

Wang, Liya; Roudgar, Ata; Eikerling, Michael

doi:10.1021/jp900965q

Cited by 81 publications

(76 citation statements)

References 76 publications

(139 reference statements)

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“…The foregoing parameters were tested for the Pt bulk and excellent agreement with experiment was obtained (e.g., for the lattice parameter, 3.98 Å (lit., 3.96 Å [38]) and cohesive energy per atom, 5.55 eV (lit., 5.84 eV [38])). Moreover, the coh E value for the 1-2 nm Pt NPs (Table 1) was in agreement with other reports [39,40]. Further details of the calculation methods for Pt dissolution and coalescence are discussed in the succeeding sections.…”

Section: Methodssupporting

confidence: 89%

First-principles calculations of the dissolution and coalescence properties of Pt nanoparticle ORR catalysts: The effect of nanoparticle shape

Escaño

2015

Nano Res.

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The degradation of Pt nanoparticles (NPs) in fuel cell cathodes leads to the loss of the precious metal catalyst. While the effect of NP size on Pt dissolution has been studied extensively, the influence of NP shape is largely unexplored. Because of the recent development of experimental methods to control the shape of metal NPs, rational guidelines/insights on the shape effects on NP stability are imperative. In this study, first-principles calculations based on density functional theory were conducted to determine the stability of 1-2 nm Pt NPs against Pt dissolution and coalescence with respect to NP shape. Toward dissolution, the stability of the Pt NPs increases in the following order: Hexagonal close-packed < icosahedral < cuboctahedral < truncated octahedral. This trend is attributed to the synergy of the oxygen adsorption strength and the local coordination of the Pt atoms. With respect to coalescence, the size of a NP is related to its propensity to coalesce or detach/migrate to form larger particles. The stability of the Pt NPs was found to increase in the following order: Hexagonal close-packed < truncated octahedral < cuboctahedral < icosahedral, and was correlated with the cohesive energies of the particles. By combining the characteristic stabilities of the shapes, new "metal-interfaced" Pt-based coreshell architectures were proposed that should be more stable than pure Pt nanoparticles with respect to both dissolution and coalescence.

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Section: Methodssupporting

confidence: 89%

First-principles calculations of the dissolution and coalescence properties of Pt nanoparticle ORR catalysts: The effect of nanoparticle shape

Escaño

2015

Nano Res.

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“…Although the flat and amorphous SiO 2 approaches a homogeneous support, surface inhomogeneities or defects cannot be excluded and may result in an inhomogeneous metal adhesion with an impact on the concentration or diffusion of atomic species as well as on the shape and orientation of the metal nanoparticles [44][45][46][47][48]. These detailed structural features may also be important for determining the rates of nanoparticle growth or decay in the presence of a reactive gas environment [4,6,35].…”

Section: Discussionmentioning

confidence: 99%

Ostwald ripening in a Pt/SiO2 model catalyst studied by in situ TEM

Simonsen

Chorkendorff

Dahl

et al. 2011

Journal of Catalysis

197

202

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Sintering of Pt nanoparticles dispersed on a planar SiO 2 support was studied by in situ transmission electron microscopy (TEM). A time-lapsed TEM image series of the Pt nanoparticles, acquired during the exposure to 10 mbar synthetic air at 650 ºC, reveal that the sintering is governed by the Ostwald ripening mechanism. The in situ TEM images also provide information about the temporal evolution of the Pt particle size distribution and of the individual nanoparticle's growth or decay. The observed Pt nanoparticle changes compare well with predictions made by mean-field kinetic models for ripening, but deviations are revealed for the time-evolution for the individual nanoparticles. A better description of the individual nanoparticle ripening is obtained by kinetic models that include local correlations between neighboring nanoparticles in the atom-exchange process.

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“…S8). Low-coordination sites are more prone to oxidation and dissolution 33,34,17 ; the potential cycling re-arranges the surface atoms (including the healing process of surface defects by Au atoms mentioned above), and the resulting smooth, high-coordinated surfaces may further increase the stability of this electrocatalyst 17 .…”

Section: Structure Of Pt ML /Pdau/c Electrocatalystmentioning

confidence: 99%

Highly stable Pt monolayer on PdAu nanoparticle electrocatalysts for the oxygen reduction reaction

et al. 2012

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stability is one of the main requirements for commercializing fuel cell electrocatalysts for automotive applications. Platinum is the best-known catalyst for oxygen reduction in cathodes, but it undergoes dissolution during potential changes while driving electric vehicles, thus hampering commercial adoption. Here we report a new class of highly stable, active electrocatalysts comprising platinum monolayers on palladium-gold alloy nanoparticles. In fuel-cell tests, this electrocatalyst with its ultra-low platinum content showed minimal degradation in activity over 100,000 cycles between potentials 0.6 and 1.0 V. under more severe conditions with a potential range of 0.6-1.4 V, again we registered no marked losses in platinum and gold despite the dissolution of palladium. These data coupled with theoretical analyses demonstrated that adding a small amount of gold to palladium and forming highly uniform nanoparticle cores make the platinum monolayer electrocatalyst significantly tolerant and very promising for the automotive application of fuel cells.

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Ab Initio Study of Stability and Site-Specific Oxygen Adsorption Energies of Pt Nanoparticles

Cited by 81 publications

References 76 publications

First-principles calculations of the dissolution and coalescence properties of Pt nanoparticle ORR catalysts: The effect of nanoparticle shape

First-principles calculations of the dissolution and coalescence properties of Pt nanoparticle ORR catalysts: The effect of nanoparticle shape

Ostwald ripening in a Pt/SiO2 model catalyst studied by in situ TEM

Highly stable Pt monolayer on PdAu nanoparticle electrocatalysts for the oxygen reduction reaction

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