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Synthesis and Characterization of Carbon Based One-Dimensional Structures: Tuning Physical and Chemical Properties
Umeå University, Faculty of Science and Technology, Department of Physics. (Nano for Energy)
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Carbon nanostructures have been extensively used in different applications; ranging from electronic and optoelectronic devices to energy conversion. The interest stems from the fact that covalently bonded carbon atoms can form a wide variety of structures with zero-, one- and two-dimensional configuration with different physical properties. For instance, while fullerene molecules (zero-dimensional carbon structures) realize semiconductor behavior, two-dimensional graphene shows metallic behavior with exceptional electron mobility. Moreover the possibility to even further tune these fascinating properties by means of doping, chemical modification and combining carbon based sub-classes into new hybrid structures make the carbon nanostructure even more interesting for practical application. 

This thesis focuses on synthesizing SWCNT and different C60 one-dimensional structures as well as tuning their properties by means of different chemical and structural modification. The purpose of the study is to have better understanding of the synthesis and modification techniques, which opens for better control over the properties of the product for desired applications.

In this thesis carbon nanotubes (CNTs) are grown by chemical vapor deposition (CVD) on iron/cobalt catalyst particles. The effect of catalyst particle size on the diameter of the grown CNTs is systematically studied and in the case of SWCNTs it is shown that the chirality distribution of the grown SWCNTs can be tuned by altering the catalyst particle composition. In further experiments, incorporation of the nitrogen atoms in SWCNTs structures is examined. A correlation between experimental characterization techniques and theoretical calculation enable for precise analysis of different types of nitrogen configuration in SWCNTs structure and in particular their effect on growth termination and electronic properties of SWCNTs are studied.

C60 one-dimensional structures are grown through a solution based method known as Liquid-liquid interfacial precipitation (LLIP). By controlling the crystal seed formation at the early stage of the growth the morphology and size of the grown C60 one-dimensional structures where tuned from nanorods to large diameter rods and tubes. We further introduce a facile solution-based method to photo-polymerize the as-grown C60 nanorods, and show that such a method crates a polymeric C60 shell around the nanorods. The polymeric C60 shell exhibits high stability against common hydrophobic C60 solvents, which makes the photo-polymerized nanorods ideal for further solution-based processing. This is practically shown by decoration of both as grown and photo-polymerized nanorods by palladium nanoparticles and comparison between their electrochemical activities. The electrical properties of the C60 nanorods are also examined by utilizing a field effect transistor geometry comprising different C60 nanorods.

In the last part of the study a variant of CNT is synthesized in which large diameter, few-walled CNTs spontaneously transform to a collapsed ribbon shape structure, the so called collapsed carbon nanotube (CCNT). By inserting C60 molecules into the duct edges of CCNT a new hybrid structure comprising C60 molecules and CCNT is synthesized and characterized. A further C60 insertion lead to reinflation of CCNTs, which eventually form few-walled CNT completely filled with C60 molecules.

Place, publisher, year, edition, pages
Umeå: Umeå University , 2015. , 71 p.
Keyword [en]
Carbon Nanotube, single-walled carbon nanotube, nitrogen doped, chemical vapor deposition, fullerene, hybrid structures
National Category
Condensed Matter Physics
Research subject
nanomaterials
Identifiers
URN: urn:nbn:se:umu:diva-97551ISBN: 978-91-7601-191-1 (print)OAI: oai:DiVA.org:umu-97551DiVA: diva2:774337
Public defence
2015-01-28, MA121, MIT Huset, Umeå, 13:00 (English)
Opponent
Supervisors
Available from: 2015-01-07 Created: 2014-12-22 Last updated: 2015-01-04Bibliographically approved
List of papers
1. Simple Dip-Coating Process for the Synthesis of Small Diameter Single-Walled Carbon Nanotubes-Effect of Catalyst Composition and Catalyst Particle Size on Chirality and Diameter
Open this publication in new window or tab >>Simple Dip-Coating Process for the Synthesis of Small Diameter Single-Walled Carbon Nanotubes-Effect of Catalyst Composition and Catalyst Particle Size on Chirality and Diameter
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2012 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 116, no 22, 12232-12239 p.Article in journal (Refereed) Published
Abstract [en]

We report on a dip-coating method to prepare catalyst particles (mixture of iron and cobalt) with a controlled diameter distribution on silicon wafer substrates by changing the solution's concentration and withdrawal velocity. The size and distribution of the prepared catalyst particles were analyzed by atomic force microscopy. Carbon nanotubes were grown by chemical vapor deposition on the substrates with the prepared catalyst particles. By decreasing the catalyst particle size to below 10 nm, the growth of carbon nanotubes can be tuned from few-walled carbon nanotubes, with homogeneous diameter, to highly pure single-walled carbon nanotubes. Analysis of the Raman radial breathing modes, using three different Raman excitation wavelengths (488, 633, and 785 nm), showed a relatively broad diameter distribution (0.8-1.4 nm) of single-walled carbon nanotubes with different chiralities. However, by changing the composition of the catalyst particles while maintaining the growth parameters, the chiralities of single-walled carbon nanotubes were reduced to mainly four different types, (12, 1), (12, 0), (8, 5), and (7, 5), accounting for about 70% of all nanotubes.

National Category
Nano Technology
Identifiers
urn:nbn:se:umu:diva-56974 (URN)10.1021/jp211064c (DOI)000304888700046 ()
Available from: 2012-07-03 Created: 2012-07-02 Last updated: 2017-12-07Bibliographically approved
2. Nitrogen Doping Mechanism in Small Diameter Single-Walled Carbon Nanotubes: Impact on Electronic Properties and Growth Selectivity
Open this publication in new window or tab >>Nitrogen Doping Mechanism in Small Diameter Single-Walled Carbon Nanotubes: Impact on Electronic Properties and Growth Selectivity
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2013 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 117, no 48, 25805-25816 p.Article in journal (Refereed) Published
Abstract [en]

Nitrogen doping in carbon nanostructures has attracted interest for more than a decade, and recent implementation of such structures in energy conversion systems has boosted the interest even more. Despite numerous studies, the structural conformation and stability of nitrogen functionalities in small diameter single-walled carbon nanotubes (SWNTs), and the impact of these functionalities on the electronic and mechanical properties of the SWNTs, are incomplete. Here we report a detailed study on nitrogen doping in SWNTs with diameters in the range of 0.8?1.0 nm, with well-defined chirality. We show that the introduction of nitrogen in the carbon framework significantly alters the stability of certain tubes, opening for the possibility to selectively grow nitrogen-doped SWNTs with certain chirality and diameter. At low nitrogen concentration, pyridinic functionalities are readily incorporated and the tubular structure is well pertained. At higher concentrations, pyrrolic functionalities are formed, which leads to significant structural deformation of the nanotubes and hence a stop in growth of crystalline SWNTs. Raman spectroscopy is an important tool to understand guest atom doping and electronic charge transfer in SWNTs. By correlating the influence of defined nitrogen functionalities on the electronic properties of SWNTs with different chirality, we make precise interpretation of experimental Raman data. We show that the previous interpretation of the double-resonance G?-peak in many aspects is wrong and instead can be well-correlated to the type of nitrogen doping of SWNTs originating from the p- or n-doping nature of the nitrogen incorporation. Our results are supported by experimental and theoretical data.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2013
National Category
Materials Chemistry Theoretical Chemistry
Identifiers
urn:nbn:se:umu:diva-84713 (URN)10.1021/jp409518m (DOI)
Conference
2014/01/17
Funder
Swedish Research Council, dnr-2010-3973
Available from: 2014-01-17 Created: 2014-01-17 Last updated: 2017-12-06Bibliographically approved
3. Water assisted growth of C-60 rods and tubes by liquid-liquid interfacial precipitation method
Open this publication in new window or tab >>Water assisted growth of C-60 rods and tubes by liquid-liquid interfacial precipitation method
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2012 (English)In: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 17, no 6, 6840-6853 p.Article in journal (Refereed) Published
Abstract [en]

C-60 nanorods with hexagonal cross sections are grown using a static liquid-liquid interfacial precipitation method in a system of C-60/m-dichlorobenzene solution and ethanol. Adding water to the ethanol phase leads instead to C-60 tubes where both length and diameter of the C-60 tubes can be controlled by the water content in the ethanol. Based on our observations we find that the diameter of the rods/tubes strongly depends on the nucleation step. We propose a liquid-liquid interface growth model of C-60 rods and tubes based on the diffusion rate of the good C-60 containing solvent into the poor solvent as well as on the size of the crystal seeds formed at the interface between the two solvents. The grown rods and tubes exhibit a hexagonal solvate crystal structure with m-dichlorobenzene solvent molecules incorporated into the crystal structure, independent of the water content. An annealing step at 200 degrees C at a pressure <1 kPa transforms the grown structures into a solvent-free face centered cubic structure. Both the hexagonal and the face centered cubic structures are very stable and neither morphology nor structure shows any signs of degradation after three months of storage.

Keyword
fullerene, C-60 rods, C-60 tubes, LLIP method, water-ethanol mixture
National Category
Physical Sciences Organic Chemistry
Identifiers
urn:nbn:se:umu:diva-57665 (URN)10.3390/molecules17066840 (DOI)000305800400045 ()
Available from: 2012-08-08 Created: 2012-08-08 Last updated: 2017-12-07Bibliographically approved
4. On the fabrication of crystalline C-60 nanorod transistors from solution
Open this publication in new window or tab >>On the fabrication of crystalline C-60 nanorod transistors from solution
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2012 (English)In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 23, no 34, 344015- p.Article in journal (Refereed) Published
Abstract [en]

Flexible and high-aspect-ratio C-60 nanorods are synthesized using a liquid-liquid interfacial precipitation process. As-grown nanorods are shown to exhibit a hexagonal close-packed single-crystal structure, with m-dichlorobenzene solvent molecules incorporated into the crystalline structure in a C-60:m-dichlorobenzene ratio of 3.2. An annealing step at 200 degrees C transforms the nanorods into a solvent-free face-centred-cubic polycrystalline structure. The nanorods are deposited onto field-effect transistor structures using two solvent-based techniques: drop-casting and dip-coating. We find that dip-coating deposition results in a preferred alignment of non-bundled nanorods and a satisfying transistor performance. The latter is quantified by the attainment of an electron mobility of 0.08 cm(2) V-1 s(-1) and an on/off ratio of >10(4) for a single-crystal nanorod transistor, fabricated with a solution-based and low-temperature process that is compatible with flexible substrates.

Place, publisher, year, edition, pages
Bristol: Institute of Physics Publishing (IOPP), 2012
National Category
Physical Sciences
Identifiers
urn:nbn:se:umu:diva-60080 (URN)10.1088/0957-4484/23/34/344015 (DOI)000307812000016 ()
Available from: 2012-10-08 Created: 2012-10-01 Last updated: 2017-12-07Bibliographically approved
5. Solution-Based Phototransformation of C-60 Nanorods: Towards Improved Electronic Devices
Open this publication in new window or tab >>Solution-Based Phototransformation of C-60 Nanorods: Towards Improved Electronic Devices
2013 (English)In: Particle & particle systems characterization, ISSN 0934-0866, E-ISSN 1521-4117, Vol. 30, no 8, 715-720 p.Article in journal (Refereed) Published
Abstract [en]

A modified liquid-liquid interface precipitation synthesis of C-60 nanorods, effects and opportunities following an in situ photochemical transformation in the liquid state, and an electronic characterization using a field-effect transistor (FET) geometry are reported. The nanorods feature a high aspect ratio of approximate to 10(3) and a notably small average diameter of 172 nm. Interestingly, it is found that a decreased nanorod diameter appears to correlate with distinctly improved electronic properties, and an average electron mobility of 0.30 cm(2) V-1 s(-1), as measured in a FET geometry, is reported for as-grown nanorods, with the peak value being an impressive 1.0 cm(2) V-1 s(-1). A photoexposure using green laser light ( = 532 nm) is demonstrated to result in the formation of a polymer-C-60 shell encapsulating a monomer-C-60 bulk; such photo-transformed nanorods exhibit an electron mobility of 4.7 x 10(-3) cm(2) V-1 s(-1). It is notable that the utilized FET geometry only probes the polymer-C-60 nanorod surface shell, and that the monomer-C-60 bulk is anticipated to exhibit a higher mobility. Importantly, photoexposed nanorods can be conveniently processed as a stabile dispersion in common hydrophobic solvents, and this finding is attributed to the insoluble character of the polymer-C-60 shell.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2013
Keyword
C-60 nanorods, nanowhiskers, field-effect transistors, liquid-liquid-interface precipitation, photopolymerization, Raman spectroscopy
National Category
Physical Chemistry Nano Technology
Identifiers
urn:nbn:se:umu:diva-84136 (URN)10.1002/ppsc.201300016 (DOI)000327250400012 ()
Available from: 2013-12-17 Created: 2013-12-16 Last updated: 2017-12-06Bibliographically approved
6. Palladium nanocrystals supported on photo-transformed C-60 nanorods: effect of crystal morphology and electron mobility on the electrocatalytic activity towards ethanol oxidation
Open this publication in new window or tab >>Palladium nanocrystals supported on photo-transformed C-60 nanorods: effect of crystal morphology and electron mobility on the electrocatalytic activity towards ethanol oxidation
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2014 (English)In: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 73, 34-40 p.Article in journal (Refereed) Published
Abstract [en]

We report on the synthesis and decoration of high-aspect-ratio crystalline C-60 nanorods (NRs) by functionalized palladium nanoparticles with an average size of 4.78 +/- 0.66 nm. In their pristine form, C-60 NRs suffer from partial damage in the solution-based decoration process resulting in poor crystallinity. However, by modifying the NR surface via in situ photochemical transformation in the liquid state, we are able to prepare highly stable NRs that retain their crystalline structure during the decoration process. Our method thus opens up for the synthesis of highly crystalline nanocomposite hybrids comprising Pd nanoparticles and C-60 NRs. Bys measuring the electron mobility of different C-60 NRs, we relate both the effect of electron mobility and crystallinity to the final electrocatalytic performance of the synthesized hybrid structures. We show that the photo-transformed C-60 NRs exhibit highly advantageous properties for ethanol oxidation based on both a better crystallinity and a higher bulk conductivity. These findings give important information in the search for efficient catalyst support.

National Category
Physical Chemistry Nano Technology
Identifiers
urn:nbn:se:umu:diva-97292 (URN)10.1016/j.carbon.2014.02.028 (DOI)000335096300004 ()
Available from: 2014-12-12 Created: 2014-12-12 Last updated: 2017-12-05Bibliographically approved
7. C60/Collapsed Carbon Nanotube Hybrids: A Variant of Peapods
Open this publication in new window or tab >>C60/Collapsed Carbon Nanotube Hybrids: A Variant of Peapods
2015 (English)In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 15, no 2, 829-834 p.Article in journal, Letter (Refereed) Published
Abstract [en]

We examine a variant of so-called carbon nanotube peapods by packing C60 molecules inside the open edge ducts of collapsed carbon nanotubes. C60 insertion is accomplished through a facile single-step solution-based process. Theoretical modeling is used to evaluate favorable low-energy structural configurations. Overfilling of the collapsed tubes allows infiltration of C60 over the full cross-section of the tubes and consequent partial or complete reinflation, yielding few-wall, large diameter cylindrical nanotubes packed with crystalline C60 solid cores.

Keyword
Peapods,  fullerenes,  collapsed carbon nanotubes,  silocrystals
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:umu:diva-96427 (URN)10.1021/nl503388f (DOI)000349578000005 ()25557832 (PubMedID)
Available from: 2014-11-20 Created: 2014-11-20 Last updated: 2017-12-05Bibliographically approved

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