Surface segregation in binary Cu–Ni and Au–Co nanoalloys and the core–shell structure stability/instability: thermodynamic and atomistic simulations

Samsonov, V. M.; Talyzin, I. V.; Kartoshkin, A. Yu.; Vasilyev, S. A.

doi:10.1007/s13204-018-0895-5

Cited by 31 publications

(21 citation statements)

References 30 publications

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“…The occupancy ratios of the atoms in the surface and core in each bimetallic NP after solidification are presented in Table 1 in the column named “0.5(A):0.5(B)”. The core–shell preference found in our MD/MC results generally agree with numerous other segregation studies carried out for various bimetallic NPs such as Cu–Ag, 22 , 24 Cu–Au, 37 Ni–Cu, Co–Au, 38 Fe–Au, 39 Ni–Fe, Co–Fe, 40 Pt–Pd, 41 and Co–Ag. 42 There are also disagreements with previous works, for example, the nanothermodynamic approach predicts that Ni segregates on Cu, 43 and DFT calculations predict surface segregation of Ag on Pt but with a core(Pt)–shell(Ag) structure, 44 whereas our results predicts Janus-like structure.…”

Section: Resultssupporting

confidence: 92%

General Trends in Core–Shell Preferences for Bimetallic Nanoparticles

et al. 2021

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Surface segregation phenomena dictate core–shell preference of bimetallic nanoparticles and thus play a crucial role in the nanoparticle synthesis and applications. Although it is generally agreed that surface segregation depends on the constituent materials’ physical properties, a comprehensive picture of the phenomena on the nanoscale is not yet complete. Here we use a combination of molecular dynamics (MD) and Monte Carlo (MC) simulations on 45 bimetallic combinations to determine the general trend on the core–shell preference and the effects of size and composition. From the extensive studies over sizes and compositions, we find that the surface segregation and degree of the core–shell tendency of the bimetallic combinations depend on the sufficiency or scarcity of the surface-preferring material. Principal component analysis (PCA) and linear discriminant analysis (LDA) on the molecular dynamics simulations results reveal that cohesive energy and Wigner–Seitz radius are the two primary factors that have an “additive” effect on the segregation level and core–shell preference in the bimetallic nanoparticles studied. When the element with the higher cohesive energy also has the larger Wigner–Seitz radius, its core preference decreases, and thus this combination forms less segregated structures than what one would expect from the cohesive energy difference alone. Highly segregated structures (highly segregated core–shell or Janus-like) are expected to form when both the relative cohesive energy difference is greater than ∼20%, and the relative Wigner–Seitz radius difference is greater than ∼4%. Practical guides for predicting core–shell preference and degree of segregation level are presented.

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Section: Resultssupporting

confidence: 92%

General Trends in Core–Shell Preferences for Bimetallic Nanoparticles

et al. 2021

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“…In [5], we presented and partially confirmed the hypothesis about the relationship between the degree of stability of nanostructures A (core)/@B (shell) and the spontaneous surface segregation of one component in binary nanoparticles A-B with an initially uniform distribution of components. According to this hypothesis, the structure (A@B or B@A) whose shell corresponds to the component that spontaneously segregates to the surface of binary nanoparticles A-B will be stable (or at least stabler than the other).…”

Section: Introductionsupporting

confidence: 62%

“…According to this hypothesis, the structure (A@B or B@A) whose shell corresponds to the component that spontaneously segregates to the surface of binary nanoparticles A-B will be stable (or at least stabler than the other). Thermodynamic and atomistic modeling [5] shows that in binary Au-Co nanoparticles especially, we should observe the surface segregation of Au as a component with energy weaker than that of Co and lower values of the bonding energy and surface tension. It was therefore concluded in [5] that Co@Au nanostructures should be stabler than their Au@Co counterparts.…”

Section: Introductionmentioning

confidence: 95%

“…Thermodynamic and atomistic modeling [5] shows that in binary Au-Co nanoparticles especially, we should observe the surface segregation of Au as a component with energy weaker than that of Co and lower values of the bonding energy and surface tension. It was therefore concluded in [5] that Co@Au nanostructures should be stabler than their Au@Co counterparts. This conclusion, which is consistent with the experimental findings in [4], was confirmed by molecular dynamics results for nanoparticles of the same size.…”

Section: Introductionmentioning

confidence: 95%

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Factors of the Stability/Instability of Bimetallic Core–Shell Nanostructures

Samsonov

Sdobnyakov

Kolosov

et al. 2021

Bull. Russ. Acad. Sci. Phys.

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According to an earlier hypothesis on the relationship between the spontaneous surface segregation of a component of binary nanoparticles A-B and the stability/instability of nanostructures of the core-shell type (A@B and B@A, where the first component corresponds to the core of a particle and the second to its shell), the stability should be the same as that of the nanostructure whose shell corresponds to the component of binary nanoparticles spontaneously segregating to the surface. This hypothesis is tested, and possible deviations from this pattern are identified through the atomistic modeling of Co@Au, Au@Co, Ni@Cu, and Cu@Ni nanostructures.

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“…Nanometals, namely metallic nanoparticles, [ 1–3 ] have become a rising star in the large family of thermal catalysts. [ 4–6 ] Compared with the traditional bulky metallic catalysts, the nanometal has a much smaller particle size and thus a much larger specific surface area, [ 7–9 ] which generates a great amount of active sites and better catalytic activities. [ 10–12 ] Also, the nanoscale particle size induces a transition of the composing atoms from metallic bonding toward individual atoms, [ 3,13,14 ] thereby increasing the concentration of dangling surface bonds and enhancing the intrinsic catalytic activities of nanometals.…”

Section: Introductionmentioning

confidence: 99%

Nanometal Thermocatalysts: Transformations, Deactivation, and Mitigation

Zhang

Pan

Zhou

et al. 2021

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Nanometals have been proven to be efficient thermocatalysts in the last decades. Their enhanced catalytic activity and tunable functionalities make them intriguing candidates for a wide range of catalytic applications, such as gaseous reactions and compound synthesis/decomposition. On the other hand, the enhanced specific surface energy and reactivity of nanometals can lead to configuration transformation and thus catalytic deactivation during the synthesis and catalysis, which largely undermines the activity and service time, thereby calling for urgent research effort to understand the deactivating mechanisms and develop efficient mitigating methods. Herein, the recent progress in understanding the configuration transformation‐induced catalytic deactivation within nanometals is reviewed. The major pathways of configuration transformations, and their kinetics controlled by the environmental factors are presented. The approaches toward mitigating the transformation‐induced deactivation are also presented. Finally, a perspective on the future academic approaches toward in‐depth understanding of the kinetics of the deactivation of nanometals is proposed.

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Surface segregation in binary Cu–Ni and Au–Co nanoalloys and the core–shell structure stability/instability: thermodynamic and atomistic simulations

Cited by 31 publications

References 30 publications

General Trends in Core–Shell Preferences for Bimetallic Nanoparticles

General Trends in Core–Shell Preferences for Bimetallic Nanoparticles

Factors of the Stability/Instability of Bimetallic Core–Shell Nanostructures

Nanometal Thermocatalysts: Transformations, Deactivation, and Mitigation

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