Engineering the Activity and Lifetime of Heterogeneous Catalysts for Carbon Nanotube Growth via Substrate Ion Beam Bombardment

Islam, Ahmad E.; Nikolaev, Pavel; Amama, Placidus B.; Saber, Sammy; Zakharov, Dmitri N.; Huffman, D.; Erford, M.; Sargent, G. A.; Semiatin, S. L.; Stach, Eric A.; Maruyama, Benji

doi:10.1021/nl501417h

Cited by 19 publications

(28 citation statements)

References 49 publications

(128 reference statements)

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“…From Fig. 2 , coverage of CNTs on pristine and damaged SS increases with barrier-layer thickness, which based on previous studies correlates with increased surface porosity and the basic environment provided by the Al x O y barrier layer 28 – 30 , 32 . Also, from the Raman data in Fig.…”

Section: Resultssupporting

confidence: 61%

“…The observed decrease in average particle size of particles formed on damaged SS demonstrates that ion beam bombardment plays a significant role in not only catalyst dewetting, but also catalyst stability. Based on our previous study, 30 we attribute the improved properties of ion beam-damaged SS to the increased porosity on the surface of SS prior to Al x O y deposition. We conclude from our results that ion beam bombardment of SS favors formation and stability of catalyst particles during CCVD, which contributes to CNT growth efficiency.…”

Section: Resultsmentioning

confidence: 98%

“…2 ), this suggests that modification via ion beam bombardment alone under the conditions used in this study is incapable of transforming SS from an “inactive” to an “active” substrate. In the case of sapphire 28 , 30 , it was possible to achieve complete transformation after ion beam damage alone, because the process created both surface porosity and increased basicity. Creation of cationic vacancies during ion beam damage, which was evidenced by an increased O/Al ratio, accounted for increased basicity.…”

Section: Discussionmentioning

confidence: 99%

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Rational Modification of a Metallic Substrate for CVD Growth of Carbon Nanotubes

Baker-Fales

Almkhelfe

et al. 2018

Sci Rep

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Growth of high quality, dense carbon nanotube (CNT) arrays via catalytic chemical vapor deposition (CCVD) has been largely limited to catalysts supported on amorphous alumina or silica. To overcome the challenge of conducting CNT growth from catalysts supported on conductive substrates, we explored a two-step surface modification that involves ion beam bombardment to create surface porosity and deposition of a thin AlxOy barrier layer to make the surface basic. To test the efficacy of our approach on a non-oxide support, we focus on modification of 316 stainless steel (SS), a well-known inactive substrate for CNT growth. Our study reveals that ion beam bombardment of SS has the ability to reduce film thickness of the AlxOy barrier layer required to grow CNTs from Fe catalysts to 5 nm, which is within the threshold for the substrate to remain conductive. Additionally, catalysts supported on ion beam-damaged SS with the same AlxOy thickness show improved particle formation, catalyst stability, and CNT growth efficiency, as well as producing CNTs with higher quality and density. Under optimal reaction conditions, this modification approach can lead to CNT growth on other nontraditional substrates and potentially benefit applications that require CNTs be grown on a conductive substrate.

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Section: Resultssupporting

confidence: 61%

Section: Resultsmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

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Rational Modification of a Metallic Substrate for CVD Growth of Carbon Nanotubes

Baker-Fales

Almkhelfe

et al. 2018

Sci Rep

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“…Amorphous alumina having high porosity has been preferred and able to result in good yield and fast growth, while single crystalline sapphire has been recognized as an “inactive” support. In light of modifying the alumina property, energetic ions bombarding onto a single-crystalline sapphire layer has been shown to turn the exposed surface into a porous layer, usable as an active catalyst support for the VA-CNT growth3334. Bearing a potential practicability issue for large scale production, the effect of this method on the resultant nanotube diameters remains to be elucidated.…”

mentioning

confidence: 99%

A Forest of Sub-1.5-nm-wide Single-Walled Carbon Nanotubes over an Engineered Alumina Support

Yang

Patscheider

et al. 2017

Sci Rep

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A precise control of the dimension of carbon nanotubes (CNTs) in their vertical array could enable many promising applications in various fields. Here, we demonstrate the growth of vertically aligned, single-walled CNTs (VA-SWCNTs) with diameters in the sub-1.5-nm range (0.98 ± 0.24 nm), by engineering a catalyst support layer of alumina via thermal annealing followed by ion beam treatment. We find out that the ion beam bombardment on the alumina allows the growth of ultra-narrow nanotubes, whereas the thermal annealing promotes the vertical alignment at the expense of enlarged diameters; in an optimal combination, these two effects can cooperate to produce the ultra-narrow VA-SWCNTs. According to micro- and spectroscopic characterizations, ion beam bombardment amorphizes the alumina surface to increase the porosity, defects, and oxygen-laden functional groups on it to inhibit Ostwald ripening of catalytic Fe nanoparticles effectively, while thermal annealing can densify bulk alumina to prevent subsurface diffusion of the catalyst particles. Our findings contribute to the current efforts of precise diameter control of VA-SWCNTs, essential for applications such as membranes and energy storage devices.

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“…31 Recently, ion bombardment was used to modify the surface properties for CNT growth. 32 It's noteworthy that the catalyst nanoparticle could act as a seed for CNT growth while remaining strongly bound to the substrate surface, in which case the growth is referred to as base-growth. On the other hand, if the catalyst nanoparticle is pushed upwards by the growing CNT, it is referred to as tip-growth, as has been shown for some Mo-and Co-containing catalysts.…”

Section: Catalyst Preparation and Treatmentmentioning

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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Engineering the Activity and Lifetime of Heterogeneous Catalysts for Carbon Nanotube Growth via Substrate Ion Beam Bombardment

Cited by 19 publications

References 49 publications

Rational Modification of a Metallic Substrate for CVD Growth of Carbon Nanotubes

Rational Modification of a Metallic Substrate for CVD Growth of Carbon Nanotubes

A Forest of Sub-1.5-nm-wide Single-Walled Carbon Nanotubes over an Engineered Alumina Support

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

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