<i>In situ</i> insight into the unconventional ruthenium catalyzed growth of carbon nanostructures

Bahri, Mounib; Dembélé, Kassiogé; Sassoye, Capucine; Debecker, Damien P.; Moldovan, Simona; Gay, Anne‐Sophie; Hirlimann, Charles; Sánchez, Clément; Ersen, Ovidiu

doi:10.1039/c8nr01227j

Cited by 12 publications

(8 citation statements)

References 45 publications

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“…Recently, Picher and Lin et al reported that orthorhombic Co 2 C was the active phase, and structural fluctuations between orthorhombic Co 2 C and Co were observed. , Zhang et al reported that CNTs grew from a cobalt carbide phase (Co 3 C or Co 2 C) . Different from the low-pressure ETEM system, windowed environmental cells (E-cells) enable in situ TEM investigations of CNT growth under atmospheric pressure. − More recently, Dembélé et al reported the growth of CNTs from Co–Pt catalyst under atmospheric pressure using an E-cell, where all metallic Co and carbide phases (Co 3 C and Co 2 C) were observed to coexist . This inconsistency on the phase structure of a Co catalyst for CNT growth calls for a systematic, thorough, and convincing investigation.…”

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confidence: 99%

Precise Identification of the Active Phase of Cobalt Catalyst for Carbon Nanotube Growth by In Situ Transmission Electron Microscopy

et al. 2020

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Revealing the active phase and structure of catalyst nanoparticles (NPs) is crucial for understanding the growth mechanism and realizing the controlled synthesis of carbon nanotubes (CNTs). However, due to the high temperature and complex environment during CNT growth, precise identification of the active catalytic phase remains a great challenge. We investigated the phase evolution of cobalt (Co) catalyst NPs during the incubation, nucleation, and growth stages of CNTs under near-atmospheric pressure using an in situ close-cell environmental transmission electron microscope (ETEM). Strict statistical analysis of the electron diffractograms was performed to accurately identify the phases of the catalyst NPs. It was found that the NPs belong to an orthorhombic Co 3 C phase that remained unchanged during CNT growth, with errors in lattice spacing <5% and in angle <2°, despite changes in their morphology and orientation. Theoretical calculations further confirm that Co 3 C is the thermodynamically preferred phase during CNT growth, with the supply of carbon atoms through the surface and NP−CNT interfacial diffusion.

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confidence: 99%

Precise Identification of the Active Phase of Cobalt Catalyst for Carbon Nanotube Growth by In Situ Transmission Electron Microscopy

et al. 2020

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“…In the present study, we succeeded in observing the early-stage evolution of oligomers from ∼5 nm in diameter in bulk solution using a liquid-state transmission electron microscopy (TEM) method, 27 which allows for the observation of the dynamics of nanoscale materials in bulk solutions, such as the aggregation of protein molecules 28,29 and the growth of carbon nanostructures. 30 Furthermore, the liquid-state TEM system allows acquisition not only of time-resolved nanoscale images, but also of electron diffraction (ED) patterns, providing structural information even of sub-ten-nanometer aggregates. It should be furthermore noted that the observation is achieved with a label-free manner without any fluorescence molecules; they affect the aggregation reaction, 31,32 preventing us from grasping the truth.…”

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confidence: 99%

Time-Resolved Observation of Evolution of Amyloid-β Oligomer with Temporary Salt Crystals

Nakajima

Yamazaki

Kimura

et al. 2020

J. Phys. Chem. Lett.

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The aggregation behavior of amyloid-β (Aβ) peptides remains unclarified despite the fact that it is closely related to the pathogenic mechanism of Alzheimer's disease.Aβ peptides form diverse oligomers with various diameters before nucleation, making clarification of the mechanism involved a complex problem with conventional macroscopic analysis methods. Time-resolved single-molecule level analysis in bulk solution is thus required to fully understand their early-stage aggregation behavior. Here, we perform time-resolved observation of the aggregation dynamics of Aβ oligomers in bulk solution using liquid-state transmission electron microscopy. Our observations reveal previously unknown behaviors. The most important discovery is that a salt crystal can precipitate even with a concentration much lower than its solubility, and it then dissolves in a short time, during which the aggregation reaction of Aβ peptides is significantly accelerated. These findings will provide new insights in the evolution of Aβ oligomer.

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“…In general, applications focus on the morphological and structural evolution of catalysts under reactive conditions that mimic gas compositions, pressure and temperatures relevant to the water gas shift [96], ethylene hydrogenation [94], CO 2 reduction [97] and CO oxidation [23,24,[98][99][100][101] reactions. Nanoreactors have also been used to investigate the catalyzed growth of materials such as carbon nanostructures [102,103] and the occurrence of strong metal-support interactions (SMSI) [77,104]. Examples of in situ TEM results acquired with gas cell TEM holders are shown in Fig.…”

Section: Gas Cells-on the Relevance Of In Situ Resultsmentioning

confidence: 99%

Quo Vadis Micro-Electro-Mechanical Systems for the Study of Heterogeneous Catalysts Inside the Electron Microscope?

et al. 2020

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During the last decade, modern micro-electro-mechanical systems (MEMS) technology has been used to create cells that can act as catalytic nanoreactors and fit into the sample holders of transmission electron microscopes. These nanoreactors can maintain atmospheric or higher pressures inside the cells as they seal gases or liquids from the vacuum of the TEM column and can reach temperatures exceeding 1000 °C. This has led to a paradigm shift in electron microscopy, which facilitates the local characterization of structural and morphological changes of solid catalysts under working conditions. In this review, we outline the development of state-of-the-art nanoreactor setups that are commercially available and are currently applied to study catalytic reactions in situ or operando in gaseous or liquid environments. We also discuss challenges that are associated with the use of environmental cells. In catalysis studies, one of the major challenge is the interpretation of the results while considering the discrepancies in kinetics between MEMS based gas cells and fixed bed reactors, the interactions of the electron beam with the sample, as well as support effects. Finally, we critically analyze the general role of MEMS based nanoreactors in electron microscopy and catalysis communities and present possible future directions.

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In situ insight into the unconventional ruthenium catalyzed growth of carbon nanostructures

Abstract: We report on the in situ analysis of the growth process of carbon nanostructures catalyzed by Ru nanoparticles using syngas, a mixture of hydrogen and CO, as the carbon source at a medium temperature (500 °C).

Cited by 12 publications

References 45 publications

Precise Identification of the Active Phase of Cobalt Catalyst for Carbon Nanotube Growth by In Situ Transmission Electron Microscopy

Precise Identification of the Active Phase of Cobalt Catalyst for Carbon Nanotube Growth by In Situ Transmission Electron Microscopy

Time-Resolved Observation of Evolution of Amyloid-β Oligomer with Temporary Salt Crystals

Quo Vadis Micro-Electro-Mechanical Systems for the Study of Heterogeneous Catalysts Inside the Electron Microscope?

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