In situ atomic imaging of coalescence of Au nanoparticles on graphene: rotation and grain boundary migration

Yuk, Jong Min; Jeong, Minwoo; Kim, SangYun; Seo, Hyeon Kook; Kim, Jihyun; Lee, Jun Young

doi:10.1039/c3cc46545d

Cited by 107 publications

(93 citation statements)

References 22 publications

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“…Interestingly, the two Au clusters are merged directly at the atomic scale, which can be attributed to the epitaxy between the clusters and YSZ. Such behavior is in striking contrast to the unification of Au nanocrystals, which is assisted by crystal rotation or grain boundary migration2324. Moreover, the whole coalescence process is completed rapidly in 210 s (Fig.…”

Section: Resultsmentioning

confidence: 95%

Atomic-Scale Observation of Migration and Coalescence of Au Nanoclusters on YSZ Surface by Aberration-Corrected STEM

Wang

Chen

et al. 2014

Sci Rep

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Unraveling structural dynamics of noble metal nanoclusters on oxide supports is critical to understanding reaction process and origin of catalytic activity in heterogeneous catalysts. Here, we show that aberration-corrected scanning transmission electron microscopy can provide direct atomic-resolution imaging of surface migration, coalescence, and atomic rearrangement of Au clusters on an Y:ZrO2 (YSZ) support. The high resolution enables us to reveal migration and coalescence process of Au clusters at the atomic scale, and to demonstrate that the coalesced clusters undergo a cooperative atomic rearrangement, which transforms the coherent into incoherent Au/YSZ interface. This approach can help to elucidate atomistic mechanism of catalytic activities and to develop novel catalysts with enhanced functionality.

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Section: Resultsmentioning

confidence: 95%

Atomic-Scale Observation of Migration and Coalescence of Au Nanoclusters on YSZ Surface by Aberration-Corrected STEM

Wang

Chen

et al. 2014

Sci Rep

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“…The characteristic sintering time by surface diffusion is

τ_{normals} = \frac{k_{normalB} T r_{p, 0}^{4}}{C D γ a^{4}}

where k B is the Boltzmann constant, T (K) is the temperature, r p,0 (m) is the particle radius, C is a constant ( C = 25), D (m 2 /s) is the diffusion coefficient, γ (N/m 2 ) is the surface tension and α (m) is the atomic size. Yuk et al observed by in situ transmission electron microscope (TEM) images of electron beam irradiated Au nanoparticles (3–7 nm) that they sinter by oriented attachment which occurs either by three‐dimensional particle orientation or by grain boundary migration, depending on particles’ contact orientation.…”

Section: Theorymentioning

confidence: 99%

“…Sintering results in multiple grains (polycrystalline particles) that are wiped out and transform into a single crystal at sufficiently long times. The results are compared with electron beam irradiation experiments of coalescing Au nanoparticles . Besides free‐standing Au nanoparticle coalescence, these simulations are quite relevant also to sintering of Au on ceramic oxide supports that do not exhibit strong affinity or metal support interactions, such as Ag on TiO 2 …”

Section: Introductionmentioning

confidence: 99%

Crystallinity dynamics of gold nanoparticles during sintering or coalescence

Goudeli

Pratsinis

2015

AIChE Journal

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The crystallinity of gold nanoparticles during coalescence or sintering is investigated by molecular dynamics. The method is validated by the attainment of the Au melting temperature that increases with increasing particle size approaching the Au melting point. The morphology and crystal dynamics of nanoparticles of (un)equal size during sintering are elucidated. The characteristic sintering time of particle pairs is determined by tracing their surface area evolution during coalescence. The crystallinity is quantified by the disorder variable indicating the system's degree of disorder. The atoms at the grain boundaries are amorphous, especially during particle adhesion and during sintering when grains of different orientation are formed. Initial grain orientation affects final particle morphology leading to exposure of different crystal surfaces that can affect the performance of Au nanoparticles (e.g., catalytic efficiency). Coalescence between crystalline and amorphous nanoparticles of different size results in polycrystalline particles of increasing crystallinity with time and temperature. Crystallinity affects the sintering rate and mechanism. Such simulations of free-standing Au nanoparticle coalescence are relevant also to Au nanoparticles on supports that do not exhibit strong affinity or strong metal support interactions.

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“…Therefore, the coalescence of reduced Sn NPs happens to a limited extent, which is consistent with the unchanged morphologies before and after carbonization (Figure S2) . Besides, the partial grain boundaries of the Sn cores resulting from particle adhesion can be clearly observed, and they are marked by yellow dashed lines in Figure d …”

Section: Resultsmentioning

confidence: 91%

Basil Seed Inspired Design for a Monodisperse Core–Shell Sn@C Hybrid Confined in a Carbon Matrix for Enhanced Lithium‐Storage Performance

Qin¹,

Liu²,

Cao³

2016

Chemistry An Asian Journal

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Tin anode materials have attracted much attention owing to their high theoretical capacity, although rapid capacity fade is commonly observed mainly because of structural degradation resulting from volume expansion. Herein, we report a versatile strategy based on a basil seed inspired design for constructing a monodisperse core-shell Sn@C hybrid confined in a carbon matrix (Sn basil seeds). Analogous to the structure of basil seeds soaked in water, Sn basil seeds are used to tackle the volume expansion problem in lithium-ion batteries. Monodisperse Sn cores are encapsulated by a thick carbon layer, which thus lowers the electrolyte contact area. The obtained Sn basil seeds are closely packed to construct a framework that supplies fast electron transport and provides a reinforced mechanical backbone. As a consequence, an ensemble of this hybrid network shows significantly enhanced lithium-storage performance with a high capacity of 870 mAh g at a current density of 0.4 A g over 600 cycles. After the intense cycling, the Sn cores transform into ultrafine nanocrystals with sizes of 3-6 nm. The structural and morphological evolution of the Sn cores can reasonably explain the gradual increase in the capacity and the long-term cycling ability of our Sn basil seeds.

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In situ atomic imaging of coalescence of Au nanoparticles on graphene: rotation and grain boundary migration

Cited by 107 publications

References 22 publications

Atomic-Scale Observation of Migration and Coalescence of Au Nanoclusters on YSZ Surface by Aberration-Corrected STEM

Atomic-Scale Observation of Migration and Coalescence of Au Nanoclusters on YSZ Surface by Aberration-Corrected STEM

Crystallinity dynamics of gold nanoparticles during sintering or coalescence

Basil Seed Inspired Design for a Monodisperse Core–Shell Sn@C Hybrid Confined in a Carbon Matrix for Enhanced Lithium‐Storage Performance

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