Shape of Cobalt and Platinum Nanoparticles Under a CO Atmosphere: A Combined In Situ TEM and Computational Catalysis Study

Vrieze, Jenoff E. De; Bremmer, G.M.; Aly, M. H.; Navarro, Violeta; Thybaut, Joris W.; Kooyman, Patricia J.; Saeys, Mark

doi:10.1021/acscatal.9b01840

Cited by 22 publications

(27 citation statements)

References 47 publications

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“…4c) are routinely possible and that the addition of the homebuilt gas feed and analysis setup to the TEM does not limit the resolution. It should be noted that the spatial resolution is similar to previous reports that have investigated different catalytic systems in situ (Kooyman et al, 2001; Hansen et al, 2002; Allard et al, 2012; Bremmer et al, 2017; Zou et al, 2017; Dembele et al, 2018; Roiban et al, 2018; Altantzis et al, 2019; De Vrieze et al, 2019; Tan et al, 2019). In a first attempt, imaging and diffraction were tested during the in situ synthesis of Pt NPs.…”

Section: Resultssupporting

confidence: 83%

“…MEMS-based nanoreactors allow for pressures up to 14 bar (Creemer et al, 2011) and temperatures up to 1,300°C (Garza et al, 2017). Several in situ TEM studies using MEMS-based nanoreactors have yielded results with different functional materials in various reductive and oxidative environments (Kooyman et al, 2001;Hansen et al, 2002;Giorgio et al, 2008;Vendelbo et al, 2014;Crozier & Hansen, 2015;Aouine et al, 2016;Bremmer et al, 2017;Zou et al, 2017;Dembele et al, 2018;Roiban et al, 2018;Altantzis et al, 2019;De Vrieze et al, 2019;Tan et al, 2019). Although most of these studies are not directly proofing the catalytic function, they still provide valuable information about structural and morphological changes of materials in various gas atmospheres at elevated temperatures.…”

Section: Introductionmentioning

confidence: 99%

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Versatile Homebuilt Gas Feed and Analysis System for Operando TEM of Catalysts at Work

et al. 2020

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Understanding how catalysts work during chemical reactions is crucial when developing efficient catalytic materials. The dynamic processes involved are extremely sensitive to changes in pressure, gas environment and temperature. Hence, there is a need for spatially resolved operando techniques to investigate catalysts under working conditions and over time. The use of dedicated operando techniques with added detection of catalytic conversion presents a unique opportunity to study the mechanisms underlying the catalytic reactions systematically. Herein, we report on the detailed setup and technical capabilities of a modular, homebuilt gas feed system directly coupled to a quadrupole mass spectrometer, which allows for operando transmission electron microscopy (TEM) studies of heterogeneous catalysts. The setup is compatible with conventional, commercially available gas cell TEM holders, making it widely accessible and reproducible by the community. In addition, the operando functionality of the setup was tested using CO oxidation over Pt nanoparticles.

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Section: Resultssupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Versatile Homebuilt Gas Feed and Analysis System for Operando TEM of Catalysts at Work

et al. 2020

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“…55 Wulff construction has been successfully applied to predict the morphology of metal nanoparticles. 23,[56][57][58][59][60][61][62][63][64][65] To consider the influence of environment, the adsorbate-dependent surface tension can be modified as the interface tension by the following equation 66,67 :…”

Section: Adsorption-induced Reshaping Of Nanoparticlesmentioning

confidence: 99%

“…According to the Wulff theorem, a crystalline with the lowest surface energy has a distinct shape in vacuum as follows: starting from an original point, O, one draws a plane that is normal to the

([], hkl)

vector at the distance

d_{hkl} = c \cdot γ_{hkl}

from O, where

c

is a constant and the quantity

γ_{hkl}

is the energy required to generate a surface of unit area normal to the

([], hkl)

vector 55 . Wulff construction has been successfully applied to predict the morphology of metal nanoparticles 23,56–65 . To consider the influence of environment, the adsorbate‐dependent surface tension can be modified as the interface tension by the following equation 66,67 :

\begin{matrix} true \\ γ_{italichkl}^{int} = {normalγ}_{italichkl} + θ (P, T) (\frac{E_{ads}}{A_{at}}), \end{matrix}

where

E_{ads}

is the adsorption energy,

θ = N_{ads} / N_{surface}

is the gas adsorption coverage on the surface (number of adsorbates,

N_{ads}

, over number of surface atoms,

N_{surface}

), and

A_{at}

is the area per surface atom.…”

Section: The Influence Of Atmosphere On Reconstructionmentioning

confidence: 99%

Insights into structure of metal nanomaterials in reactive environments

Han

Duan

Zhu

et al. 2021

WIREs Comput Mol Sci

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Metal nanomaterials are of great importance in the field of heterogeneous catalysis. In general, the catalytic performances of metal nanomaterials are determined by the structures. However, far from being static, dynamic reconstruction of metal nanomaterials constantly occurs in reactive environments, resulting in different catalytic activities. This review summarizes the latest progress of theoretical understanding of the driving forces for the structural changes. In the first part, some typical ex situ and in situ experimental observations of catalysts in reactive environments are briefly introduced, including the changes of shape, size, and alloy composition of metal or bimetallic nanomaterials. Next, we review the state-of-the-art advancement of the theoretical calculations and simulation methods to understand these experimental observations, and categorize them according to the different driving forces, for example, the oxidation and reduction effects, adsorption-induced reconstruction. Moreover, this review provides many examples for the quantitative agreement between theoretical modeling and experimental observations, which indicates the potential applications for the rational design of high-performance metal nanocatalysts in real reactions.

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“…One previous review summarizes them as electronic, geometric, steric, and ordering effects . Improving our understanding of intermetallic effects in catalysis is not trivial and requires a combination of characterization and computation techniques. , …”

Section: Introductionmentioning

confidence: 99%

Silica-Encapsulated Intermetallic Nanoparticles for Highly Active and Selective Heterogeneous Catalysis

2021

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Conspectus Intermetallic nanoparticles (iNPs) have been the subject of many recent reports for their demonstrated applications as highly active and selective heterogeneous catalysts. As a subclass of alloys, intermetallic compounds possess ordered crystal structures and, therefore, well-defined atomic environments, unlike the solid solution of alloys whose atomic arrangements are random and locally unpredictable. Catalytically active iNPs typically contain a group 8–10 transition metals as the “active” metals. They usually also include an “inactive” metal that does not directly participate in the catalytic reaction but can significantly modify the active metal’s behavior. The choice of the inactive metal component can range across the periodic table. A few general challenges remain to design iNPs as heterogeneous catalysts with outstanding performance. Synthetically, the high surface energy of small nanoparticles is prone to their aggregation, while maximizing the surface-to-volume ratios is highly desired for efficient noble metal utilization. Additionally, even though the formation of bulk intermetallic compounds has been extensively studied, the formation of intermetallic phases at the nanoscale can behave differently. For example, the formation temperatures of iNPs are often drastically different from those predicted from the bulk phase diagrams. This behavior often leads to further challenges in the synthesis of iNPs. In addition to synthetic challenges, it is also critical to demonstrate the performance of iNPs in catalysis and establish the structure–property relationships. Instrumental and computational techniques often assist the understanding of catalytic properties. Due to the long-range order of intermetallic structure, various electron and X-ray techniques are often used to precisely determine the structure of iNPs. Structural modeling in density functional theory (DFT) calculation can also benefit from such ordered structures. These techniques have siginificantly improved the understanding of enhanced catalytic properties of iNPs in thermo-, electro-, and photocatalysis. Hydrogenation of furfural to furfuryl alcohol, for example, is a model reaction where PtSn iNPs show enhanced activity and chemoselectivity in hydrogenating CO rather than CC bonds. This superior catalytic performance can be correlated to the change in the geometric and electronic surface structure of the PtSn iNPs based on careful instrumental and computational characterizations. Additionally, intermetallic surfaces can be further modified by ligands or defects. While adding complexity to iNP systems, these modifiers provide additional control over their catalytic properties. In this Account, taking encapsulated iNPs in mesoporous silica as an example, we review the current strategies to develop iNPs as high-performance heterogeneous catalysts, with insights on the distinct formation behavior of iNPs compared to bulk intermetallic materials. We then highlight thermo- and electro-catalysis reactions to which these iNP catalysts a...

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Shape of Cobalt and Platinum Nanoparticles Under a CO Atmosphere: A Combined In Situ TEM and Computational Catalysis Study

Cited by 22 publications

References 47 publications

Versatile Homebuilt Gas Feed and Analysis System for Operando TEM of Catalysts at Work

Versatile Homebuilt Gas Feed and Analysis System for Operando TEM of Catalysts at Work

Insights into structure of metal nanomaterials in reactive environments

Silica-Encapsulated Intermetallic Nanoparticles for Highly Active and Selective Heterogeneous Catalysis

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