From metastability to equilibrium during the sequential growth of Co–Ag supported clusters: a real-time investigation

Andreazza, Pascal; Lemoine, Asseline; Coati, Alessandro; Nelli, Diana; Ferrando, Riccardo; Garreau, Y.; Creuze, Jérôme; Andreazza‐Vignolle, C.

doi:10.1039/d0nr08862e

Cited by 20 publications

(43 citation statements)

References 49 publications

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“…In any case, the final morphology of the nanoparticle can be understood and even predicted by computational methods. Although a thorough description of these methods is beyond the scope of this review, the Monte Carlo method [41,42] along with molecular dynamics [43][44][45] calculations should be referenced, as they play a key role in comprehension of the formation and morphology of heterogeneous nanoparticles.…”

Section: Gas Phase Methods For the Synthesis Of Multi-element Nanoparticlesmentioning

confidence: 99%

Gas Phase Synthesis of Multi-Element Nanoparticles

et al. 2021

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The advantages of gas-phase synthesis of nanoparticles in terms of size control and flexibility in choice of materials is well known. There is increasing interest in synthesizing multi-element nanoparticles in order to optimize their performance in specific applications, and here, the flexibility of material choice is a key advantage. Mixtures of almost any solid materials can be manufactured and in the case of core–shell particles, there is independent control over core size and shell thickness. This review presents different methods of producing multi-element nanoparticles, including the use of multiple targets, alloy targets and in-line deposition methods to coat pre-formed cores. It also discusses the factors that produce alloy, core–shell or Janus morphologies and what is possible or not to synthesize. Some applications of multi-element nanoparticles in medicine will be described.

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Section: Gas Phase Methods For the Synthesis Of Multi-element Nanoparticlesmentioning

confidence: 99%

Gas Phase Synthesis of Multi-Element Nanoparticles

et al. 2021

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“…Specifically, the study of growth processes in very clean environments, such as the gas phase [7], is essential to unravel the dominant pathways leading to the growth of nanoparticles of different shapes. These studies often take advantage of combined experiment-simulation efforts [8][9][10][11][12][13][14][15][16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Octahedral Growth of PtPd Nanocrystals

et al. 2021

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PtPd nanoparticles are among the most widely studied nanoscale systems, mainly because of their applications as catalysts in chemical reactions. In this work, a combined experimental-theoretical study is presented about the dependence of growth shape of PtPd alloy nanocrystals on their composition. The particles are grown in the gas phase and characterized by STEM-HRTEM. PtPd nanoalloys present a bimodal size distribution. The size of the larger population can be tuned between 3.8 ± 0.4 and 14.1 ± 2.0 nm by controlling the deposition parameters. A strong dependence of the particle shape on the composition is found: Pd-rich nanocrystals present more rounded shapes whereas Pt-rich ones exhibit sharp tips. Molecular dynamics simulations and excess energy calculations show that the growth structures are out of equilibrium. The growth simulations are able to follow the growth shape evolution and growth pathways at the atomic level, reproducing the structures in good agreement with the experimental results. Finally the optical absorption properties are calculated for PtPd nanoalloys of the same shapes and sizes grown in our experiments.

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“…Recent in situ and real-time investigations of the structural and morphological evolution during the sequential deposition in ultra high vacuum confirmed the interest of these interpretations and methods. [41,60]…”

Section: Discussionmentioning

confidence: 99%

“…In the differential method, the partial structure factors were first extracted from the difference between the intensities measured at different energies with various levels of approximation. [41] At this stage a qualitative interpretation of the data is possible, prior to model fitting. This allows the selection of relevant morphological models.…”

Section: Analysis Methodsmentioning

confidence: 99%

Out-of-equilibrium supported Pt-Co core-shell nanoparticles stabilized by kinetic trapping at room temperature

Khelfane

Andreazza‐Vignolle

Ramos

et al. 2022

Eur. Phys. J. Appl. Phys.

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The chemical stability of supported CoPt nanoparticles in out-of-equilibrium core-shell configurations was investigated mainly by anomalous grazing incidence small angle x-ray scattering (AGISAXS) in association with combined transmission electron microscopy and x-ray absorption spectroscopy. CoPt nanoparticles were prepared at room temperature by ultrahigh vacuum atom beam deposition using two different routes: simultaneous deposition of the two metals (CoPt) or sequential deposition. In this last case, Co deposition on a Pt-core (Pt@Co) and the reverse configuration (Co@Pt) are explored. In the Pt@Co case, our experimental analysis of 2.5nm particles show the stability of a Pt rich-core (80% Pt) surrounded by a two-monolayers-thick Co shell. In the reverse case, the core-shell structure is also stabilized, while the codeposited sample leads to an alloyed structure. These results suggest that the growth kinetics can trap the thermodynamically non-favorable core-shell structure even for this system which has a high alloying tendency. Besides the lack of atom mobility at room temperature, this stabilization maybe associated with core strain effects. Post thermal treatment of core-shell samples induces a structural transition from the core-shell configuration to the equilibrium alloyed configuration. This study demonstrates that the element-selective scattering technique, AGISAXS is highly efficient for the extraction of chemical segregation information from multi-component supported nanoparticles, such as core-shell structures, up to ultimate small sizes.

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From metastability to equilibrium during the sequential growth of Co–Ag supported clusters: a real-time investigation

Abstract: Real time analysis of Co atom incorporation in Ag nanoparticles, followed almost atom-by-atom by combined X-ray scattering and molecular-dynamics methods: from the sub-surface position to quasi-Janus then core–shell structures.

Cited by 20 publications

References 49 publications

Gas Phase Synthesis of Multi-Element Nanoparticles

Gas Phase Synthesis of Multi-Element Nanoparticles

Octahedral Growth of PtPd Nanocrystals

Out-of-equilibrium supported Pt-Co core-shell nanoparticles stabilized by kinetic trapping at room temperature

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