Thermal Stability of Core–Shell Nanoparticles: A Combined in Situ Study by XPS and TEM

Bonifacio, Cecile S.; Carenco, Sophie; Wu, Chenghao; House, Stephen D.; Bluhm, Hendrik; Yang, Judith C.

doi:10.1021/acs.chemmater.5b01862

Cited by 81 publications

(64 citation statements)

References 58 publications

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“…Alternatively, the aggregates of separate mineral NPs will form alloys with the temperature increase (Bonifacio et al 2015). For example, given the paucity of information on the occurrence of Tl NPs in well-investigated pyrite samples suggests that Tl preferentially dissolves into the pyrite matrix (see Fig.…”

Section: Role Of Fluid Composition and Temperaturementioning

confidence: 99%

Constraints on the solid solubility of Hg, Tl, and Cd in arsenian pyrite

Deditius

Reich²

2016

American Mineralogist

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Arsenic-rich (arsenian) pyrite can contain up to tens of thousands of parts per million (ppm) of toxic heavy metals such as Hg, Tl, and Cd, although few data are available on their solid solubility behavior. When a compilation of Hg, Tl, and Cd analyses from different environments are plotted along with As in a M(Hg, Tl, and Cd)-As log-log space, the resulting wedge-shaped distribution of data points suggests that the solid solubility of the aforementioned metals is strongly dependent on the As concentration of pyrite. The solid solubility limits of Hg in arsenian pyrite-i.e., the upper limit of the wedge-shaped zone in compositional space-are similar to the one previously defined for Au by ), whereas the solubility limit of Tl in arsenian pyrite is approximated by a ratio of Tl/As = 1. In contrast, and despite a wedge-shaped distribution of Cd-As data points for pyrite in Cd-As log-log space, the majority of Cd analyses reflect the presence of mineral particles of Cd-rich sphalerite and/or CdS. Based on these data, we show that arsenian pyrite with M/As ratios above the solubility limit of Hg and Tl contain nanoparticles of HgS, and multimetallic Tl-Hg mineral nanoparticles. These results indicate that the uptake of Hg and Tl in pyrite is strongly dependent on As contents, as it has been previously documented for metals such as Au and Cu. Cadmium, on the other hand, follows a different behavior and its incorporation into the pyrite structure is most likely limited by the precipitation of Cd-rich nanoparticulate sphalerite. The distribution of metal concentrations below the solubility limit suggests that hydrothermal fluids from which pyrite precipitate are dominantly undersaturated with respect to species of Hg and Tl, favoring the incorporation of these metals into the pyrite structure as solid solution. In contrast, the formation of metallic aggregates of Hg and Tl or mineral nanoparticles in the pyrite matrix occurs when Hg and Tl locally oversaturate with respect to their solid phases at constant temperature. This process can be kinetically enhanced by high-to-medium temperature metamorphism and thermal processing or combustion, which demonstrates a retrograde solubility for these metals in pyrite.

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Section: Role Of Fluid Composition and Temperaturementioning

confidence: 99%

Constraints on the solid solubility of Hg, Tl, and Cd in arsenian pyrite

Deditius

Reich²

2016

American Mineralogist

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“…The temperature was then increase to 180 °C and maintained for one hour in order to fully react the Co(0) precursor with the nickel nanoparticles. After isolation from the reaction medium by centrifugation, the nanoparticles presented a core‐shell morphology with nickel in the core and cobalt in the shell (Figure ) . By design, it is possible to control independently the core diameter (cf.…”

Section: Designing Metal Nanoparticles and Nanoalloysmentioning

confidence: 99%

“…Surface reactivity of the nanoparticles was high when the shell of cobalt was present: a thin layer of ca 1 nm of amorphous cobalt oxide formed as soon as the nanoparticles where exposed to ambient conditions, as showed by both X‐ray photoelectron spectroscopy (XPS) and EDS …”

Section: Designing Metal Nanoparticles and Nanoalloysmentioning

confidence: 99%

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Designing Nanoparticles and Nanoalloys with Controlled Surface and Reactivity

Carenco

2018

The Chemical Record

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Designing well-defined nanoparticles and nanoalloys is a tremendous way to achieve in-depth understanding of their intrinsic properties. In particular, structure and composition of the core and the surface of nanoalloys can be investigated by a combination of state-of-the-art in situ microscopy and spectroscopy. These nanoalloys represent a playground to establish structure-properties relationships within the nano-matter. They provide a much needed understanding of the distribution of each element within the nanoparticles, depending on the environment (gaseous atmosphere, temperature, etc.). This distribution may evolve over time. Lighter elements, such as phosphorus, are critical to the reactivity of the nanoparticle's surface in reactions such as CO or CO hydrogenation. Here, the rational design of nanoalloys will be discussed (reactants choice, composition control), in relation with their surface state. Consequences on heterogeneous and homogeneous catalytic reactions, as well as for energy storage and conversion, will be illustrated through examples.

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“…In situ transmission electron microscopy (TEM) is a powerful platform to observe such evolutions at the nanometer/atomic scale, which provides one of the best solutions for thermal stability studies. For example, the thermal stability and structural reconfiguration of Ni-Co core-shell nanoparticles were investigated through in situ TEM and XPS, which systematically reveals core-shell reconfiguration and is crucial for their utilization under high-temperature conditions [11]. By means of in situ heating TEM, the temperature-dependent diffusion process was studied, and an inversion of the core-shell structure from Ni-Au to Au-Ni was observed at 400 • C [12].…”

Section: Introductionmentioning

confidence: 99%

Structural Core-Shell beyond Chemical Homogeneity in Non-Stoichiometric Cu5FeS4 Nano-Icosahedrons: An in Situ Heating TEM Study

et al. 2019

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Thermal stability of core-shell structured nanoparticles is of vital importance to their practical applications at elevated temperature. Understanding the evolution of chemical distribution and the crystal structure of core-shell nanostructures with temperature variation at the nanoscale will open the route for practical applications and property enhancement of nanoparticles through proper design of new nanomaterials. In this study, core-shell non-stoichiometric Cu5FeS4 icosahedral nanoparticles were investigated by in situ heating transmission electron microscopy. Compared to the high structural and compositional stability at room temperature, the interdiffusion of Cu and Fe atoms became significant, ending up with disappearance of chemical difference in the core and shell over 300 °C. In contrast, different crystal structures of the core and shell were preserved even after heating at 350 °C, indicating the high structural stability. The inconsistency between chemical composition and crystal structure should be ascribed to the interaction between the intrinsic strain existing in the icosahedrons and various structures of this material system. In other words, the geometrically intrinsic strain of the nano-icosahedrons is helpful to modulate/maintain the core-shell structure. These findings open new opportunities for revealing the thermal stability of core-shell nanostructures for various applications and are helpful for the controllable design of new core-shell nanostructures.

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Thermal Stability of Core–Shell Nanoparticles: A Combined in Situ Study by XPS and TEM

Cited by 81 publications

References 58 publications

Constraints on the solid solubility of Hg, Tl, and Cd in arsenian pyrite

Constraints on the solid solubility of Hg, Tl, and Cd in arsenian pyrite

Designing Nanoparticles and Nanoalloys with Controlled Surface and Reactivity

Structural Core-Shell beyond Chemical Homogeneity in Non-Stoichiometric Cu5FeS4 Nano-Icosahedrons: An in Situ Heating TEM Study

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