Fast ‘<i>Operando</i>’ electron nanotomography

Roiban, Lucian; Li, S.; Aouine, M.; Tuel, A.; Farrusseng, David; Épicier, Thierry

doi:10.1111/jmi.12557

Cited by 33 publications

(29 citation statements)

References 37 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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“…Once formed, the particle is usually too large to pass through the zeolite shell and the yolk–shell composite can be calcined or reduced at high temperature without any changes in the particle size. In the particular case of Ag, in situ environmental TEM observations of TPA + ‐containing hollow crystals heated under O 2 atmosphere showed that nanoparticles disappeared at 450 °C, which corresponds to the temperature of decomposition of organic molecules . Decomposition of organic molecules liberates the porosity of the zeolite and enables oxygen to penetrate the cavity and oxidize Ag NPs.…”

Section: Applications: Encapsulation Methodsmentioning

confidence: 99%

Hollow Zeolite Single Crystals: Synthesis Routes and Functionalization Methods

Tuel

Farrusseng

2018

Small Methods

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when reaction intermediates or products have not enough space to form. [6][7][8] However, the ultra-microporous dimension of zeolite pores makes that catalytic activity is often limited by diffusion and that active sites deeply buried under the surface of the crystals are hardly accessible to molecules. As a consequence, only a fraction of the crystals are effectively used in catalysis, which represents a major drawback in many reactions catalyzed by zeolites, as they do not operate at their full volume. [9] Many strategies have been developed to minimize the effect of internal diffusion on reaction rates and the subject is still of great interest for both academic and industrial researchers. Transport in zeolite micropores can be significantly improved using nanosized zeolites, typically with individual crystals smaller than a few hundreds of nanometers. [10][11][12] Nanosized crystals are generally obtained by modifying standard hydrothermal crystallization conditions for example by decreasing temperature, shortening the crystallization period, increasing supersaturation, or by adding growth inhibitors to the synthesis gel. One of the most famous examples of growth inhibition concerns the preparation of zeolite nanosheets with specific structure directing agents containing a diquaternary ammonium head group and a long hydrophobic surfactant chain. [13][14][15] These molecules force the zeolite framework to grow perpendicularly to the alkyl chains, leading to a multilamellar stacking of sheets with a thickness corresponding to a few unit cells. However, the synthesis of zeolite crystals with a size below 500 nm is not always obvious. In addition, it is neither evident to reduce the size of the crystal while keeping all other structural parameters the same. Indeed decreasing the size often results in changes in the zeolite composition and thus properties. [16][17][18] Transport can also be greatly facilitated by using "mesoporous" zeolites, i.e., zeolites that possess a secondary array of pores in addition to structural micropores. Such zeolites are usually obtained by dissolving some parts of the framework under alkaline (desilication), acidic (dealumination), or hydrothermal conditions. [9,[19][20][21][22][23][24][25][26] Since diffusion in mesopores is generally several orders of magnitude faster than in micropores, those microporous-mesoporous hierarchical zeolites showed improved catalytic properties for many reactions involving large molecules. [27][28][29][30][31][32][33] However, the mesopore size distribution is difficult to control and the benefits on catalytic reaction rates can be partially annihilated by significant changes in framework Hollow zeolite single crystals represent a new class of materials that have received considerable attention over the last decade. Besides facilitating the transport of molecules in zeolite crystals, the cavity present in hollow crystals offers many possibilities for encapsulating active species and constitutes a closed space that can be used as a nanoreactor. However,...

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“…A major drawback of electron tomography is the time needed to acquire a full tomographic tilt series, which will hamper the investigation of fast processes in 3D. 28 In addition, long exposure times may cause undesired changes within the NPs, making it difficult to differentiate between heat-induced and electron beam induced changes. Therefore, one of the emerging challenges in the field of electron tomography is to improve the speed of tomography experiments, while preserving the quality of the 3D reconstructions.…”

Section: Introductionmentioning

confidence: 99%