Evolution in Catalyst Morphology Leads to Carbon Nanotube Growth Termination

Kim, Seung Min; Pint, Cary L.; Amama, Placidus B.; Zakharov, Dmitri N.; Hauge, Robert H.; Maruyama, Benji; Stach, Eric A.

doi:10.1021/jz9004762

Cited by 182 publications

(204 citation statements)

References 27 publications

(47 reference statements)

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“…As discussed above, environmental studies can be performed in an ETEM with the use of conventional sample holders (Hansen et al, 2001;Helveg et al, 2004;Kim et al, 2010;Simonsen et al, 2010) or in a traditional TEM by use of a dedicated sample holder with a high pressure cell (Creemer et al, 2008). In both cases the setup defines the boundary conditions regarding gas, pressure and temperature.…”

Section: The Value Of Complementary Experiments -Bridging Gapsmentioning

confidence: 99%

Exploring the environmental transmission electron microscope

Wagner

Cavalca

Damsgaard

et al. 2012

Micron

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a b s t r a c tThe increasing interest and development in the field of in situ techniques have now reached a level where the idea of performing measurements under near realistic conditions has become feasible for transmission electron microscopy (TEM) while maintaining high spatial resolution.In this paper, some of the opportunities that the environmental TEM (ETEM) offers when combined with other in situ techniques will be explored, directly in the microscope, by combining electron-based and photon-based techniques and phenomena. In addition, application of adjacent setups using sophisticated transfer methods for transferring the specimen between specialized in situ equipment without compromising the concept of in situ measurements will be exploited. The opportunities and techniques are illustrated by studies of materials systems of Au/MgO and Cu 2 O in different gaseous environments.

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Section: The Value Of Complementary Experiments -Bridging Gapsmentioning

confidence: 99%

Exploring the environmental transmission electron microscope

Wagner

Cavalca

Damsgaard

et al. 2012

Micron

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“…However, it is clearly observed in this movie that even though a catalyst particle is surrounded by a graphitic shell, it can still nucleate and grow CNT by lifting up the surrounding carbon shell. This observation might be quite relevant to the experimental result in which the hydrocarbon concentration changed from 0.1 to 1% of C 2 H 2 of total process gases but did not critically affect the life-time or activity of Fe catalysts [18,19]. Also, the role of water in extending the life-time of Fe catalysts is claimed to remove the amorphous carbon or carbon shells surrounding the catalyst particles and thus recovering catalytic activity [15], but this observation appears to better support some other mechanism; perhaps Ostwald ripening inhibition, as the role of water in the super-growth of CNT forests or carpets [17].…”

Section: In-situ Cnt Growthmentioning

confidence: 76%

“…Along with lots of attempts to optimize CNT growth parameters, there has also been a great deal of effort to understand the mechanisms of growth termination. Even though several plausible mechanisms have been proposed (carbide formation of catalyst particles [11], mechanical stresses exerted on the growing array [12], and others), a recent review paper [13] introduced two mechanisms considered the most probable for the termination of CNT growth: carbon over-layer formation [14,15] and dynamic morphological evolution of catalyst particles [16][17][18][19]. For the growth termination mechanism by carbon over-layer formation, as CNT growth proceeds, amorphous carbon or a carbon over-layer starts to accumulate on the active catalyst surfaces.…”

Section: In-situ Growth Of Cntmentioning

confidence: 99%

Investigation of carbon nanotube growth termination mechanism by in-situ transmission electron microscopy approaches

Kim¹,

Jeong²,

Kim³

2013

Carbon letters

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In this work, we report in-situ observations of changes in catalyst morphology, and of growth termination of individual carbon nanotubes (CNTs), by complete loss of the catalyst particle attached to it. The observations strongly support the growth-termination mechanism of CNT forests or carpets by dynamic morphological evolution of catalyst particles induced by Ostwald ripening, and sub-surface diffusion. We show that in the tip-growth mode, as well as in the base-growth mode, the growth termination of CNT by dissolution of catalyst particles is plausible. This may allow the growth termination mechanism by evolution of catalyst morphology to be applicable to not only CNT forest growth, but also to other growth methods (for example, floating-catalyst chemical vapor deposition), which do not use any supporting layer or substrate beneath a catalyst layer.

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“…9,16,18,36,[98][99][100] Studying the mechanochemical aspects of CNT growth, wherein the effects of mechanical forces on the catalytic process are analyzed both experimentally and numerically, is an area of current research and will enable better understating and control on the CNT growth process. A deeper understanding of all the competing deactivation mechanisms and identifying the dominant ones will open the door for approaches to overcome them.…”

Section: Outlook On Remaining Challengesmentioning

confidence: 99%

Data-driven understanding of collective carbon nanotube growth by in situ characterization and nanoscale metrology

Bedewy

2016

J. Mater. Res.

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Aligned carbon nanotubes (CNTs) possess great potential for transforming the fabrication of advanced interfacial materials for energy and mass transport as well as for structural composites. Realizing this potential, however, requires building a deeper understanding and exercising greater control on the atomic scale physicochemical processes underlying the bottom-up synthesis and self-organization of CNTs. Hence, in situ nanoscale metrology and characterization techniques were developed for interrogating CNTs as they grow, interact, and self-assemble. This article presents an overview of recent research on characterization of CNT growth by chemical vapor deposition (CVD), organized into three categories based on the growth stage, for which each technique provides information: (I) catalyst preparation and treatment, (II) catalytic activation and CNT nucleation, and (III) CNT growth and termination. Combining all three categories together provides insights into building the process-structure relationship, and paves the way for producing tailored CNT structures having desired properties for target applications.

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Evolution in Catalyst Morphology Leads to Carbon Nanotube Growth Termination

Cited by 182 publications

References 27 publications

Exploring the environmental transmission electron microscope

Exploring the environmental transmission electron microscope

Investigation of carbon nanotube growth termination mechanism by in-situ transmission electron microscopy approaches

Data-driven understanding of collective carbon nanotube growth by in situ characterization and nanoscale metrology

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