| 1. |
- Abou-Hamad, Edy, et al.
(author)
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Molecular dynamics and phase transition in one-dimensional crystal of C60 encapsulated inside single wall carbon nanotubes
- 2009
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In: ACS Nano. - Washington, DC 20036 USA : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 3:12, s. 3878-3883
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Journal article (peer-reviewed)abstract
- One-dimensional crystals of 25% 13C-enriched C60 encapsulated inside highly magnetically purified SWNTs were investigated by following the temperature dependence of the 13C NMR line shapes and the relaxation rates from 300 K down to 5 K. High-resolution MAS techniques reveal that 32% of the encapsulated molecules, so-called the C60α, are blocked at room temperature and 68%, labeled C60β, are shown to reversly undergo molecular reorientational dynamics. Contrary to previous NMR studies, spin−lattice relaxation time reveals a phase transition at 100 K associated with the changes in the nature of the C60β dynamics. Above the transition, the C60β exhibits continuous rotational diffusion; below the transition, C60β executes uniaxial hindered rotations most likely along the nanotubes axis and freeze out below 25 K. The associated activation energies of these two dynamical regimes are measured to be 6 times lower than in fcc-C60, suggesting a quiet smooth orientational dependence of the interaction between C60β molecules and the inner surface of the nanotubes.
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| 2. |
- Barzegar, Hamid Reza, et al.
(author)
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Electrostatically Driven Nanoballoon Actuator
- 2016
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In: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 16:11, s. 6787-6791
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Journal article (peer-reviewed)abstract
- We demonstrate an inflatable nanoballoon actuator based on geometrical transitions between the inflated (cylindrical) and collapsed (flattened) forms of a carbon nanotube. In situ transmission electron microscopy experiments employing a nanoelectromechanical manipulator show that a collapsed carbon nanotube can be reinflated by electrically charging the nanotube, thus realizing an electrostatically driven nanoballoon actuator. We find that the tube actuator can be reliably cycled with only modest control voltages (few volts) with no apparent wear or fatigue. A complementary theoretical analysis identifies critical parameters for nanotube nanoballoon actuation.
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| 3. |
- Barzegar, Hamid Reza, et al.
(author)
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Self-assembled PCBM nanosheets : a facile route to electronic layer-on-Layer heterostructures
- 2018
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In: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 18:2, s. 1442-1447
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Journal article (peer-reviewed)abstract
- We report on the self-assembly of semicrystalline [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) nanosheets at the interface between a hydrophobic solvent and water, and utilize this opportunity for the realization of electronically active organic/organic molecular heterostructures. The self-assembled PCBM nanosheets can feature a lateral size of >1 cm2 and be transferred from the water surface to both hydrophobic and hydrophilic surfaces using facile transfer techniques. We employ a transferred single PCBM nanosheet as the active material in a field-effect transistor (FET) and verify semiconductor function by a measured electron mobility of 1.2 × 10–2 cm2 V–1 s–1 and an on–off ratio of ∼1 × 104. We further fabricate a planar organic/organic heterostructure with the p-type organic semiconductor poly(3-hexylthiophene-2,5-diyl) as the bottom layer and the n-type PCBM nanosheet as the top layer and demonstrate ambipolar FET operation with an electron mobility of 8.7 × 10–4 cm2 V–1 s–1 and a hole mobility of 3.1 × 10–4 cm2V–1 s–1.
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| 4. |
- Barzegar, Hamid Reza, et al.
(author)
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Spontaneous twisting of a collapsed carbon nanotube
- 2017
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In: Nano Reseach. - : Tsinghua University Press. - 1998-0124 .- 1998-0000. ; 10:6, s. 1942-1949
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Journal article (peer-reviewed)abstract
- We study the collapsing and subsequent spontaneous twisting of a carbon nanotube by in situ transmission electron microscopy (TEM). A custom-sized nanotube is first created in the microscope by selectively extracting shells from a parent multi-walled tube. The few-walled, large-diameter daughter nanotube is driven to collapse via mechanical stimulation, after which the ribbon-like collapsed tube spontaneously twists along its long axis. In situ diffraction experiments fully characterize the uncollapsed and collapsed tubes. The experimental observations and associated theoretical analysis indicate that the origin of the twisting is compressive strain.
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| 5. |
- Barzegar, Hamid Reza, et al.
(author)
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Synthesis of graphene nanoribbons inside boron nitride nanotubes
- 2016
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In: Physica status solidi. B, Basic research. - : Wiley. - 0370-1972 .- 1521-3951. ; 253:12, s. 2377-2379
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Journal article (peer-reviewed)abstract
- We report on bottom-up synthesis of graphene nanoribbons inside boron nitride nanotubes, using coronene molecules as building blocks. The synthesized ribbons are one or two coronene molecules wide, depending on the diameter of the host nanotube. The encapsulated carbon nanostructures can be eliminated from the inner cavity of the filled boron nitride nanotube via oxidation without any damage to the nanotube structure.
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| 6. |
- Dunn, Gabriel, et al.
(author)
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Selective Insulation of Carbon nanotubes
- 2017
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In: Physica status solidi. B, Basic research. - : Wiley-VCH Verlagsgesellschaft. - 0370-1972 .- 1521-3951. ; 254:11
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Journal article (peer-reviewed)abstract
- We demonstrate a method for the selective encapsulation of carbonnanotubes in thin parylene films using iron as a sacrificial lift-off layer. Theiron serves as an inhibitor of parylene deposition and prevents the parylenemolecules from linking, thus facilitating selective area coating after lift-off.
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| 7. |
- Gracia-Espino, Eduardo, et al.
(author)
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Coronene-based graphene nanoribbons insulated by boron nitride nanotubes : electronic properties of the hybrid structure
- 2018
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In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 3:10, s. 12930-12935
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Journal article (peer-reviewed)abstract
- We present a theoretical study on the formation of graphene nanoribbons-via polymerization of coronene molecules-inside the inner cavity of boron nitride nanotubes. We examine the electronic property of the hybrid system, and we show that the boron nitride nanotube does not significantly alter the electronic properties of the encapsulated graphene nanoribbon. Motivated by previous experimental works, we examine graphene nanoribbons with two different widths and investigate probable scenarios for defect formation and/or twisting of the resulting graphene nanoribbons and their effect on the electronic properties of the hybrid system.
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| 8. |
- Gracia-Espino, Eduardo, et al.
(author)
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Fabrication of One-Dimensional Zigzag [6,6]-Phenyl-C-61-Butyric Acid Methyl Ester Nanoribbons from Two-Dimensional Nanosheets
- 2015
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In: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 9:10, s. 10516-10522
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Journal article (peer-reviewed)abstract
- One-dimensional (10) zigzag [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) nanoribbons are produced by folding two-dimensional ultrathin PCBM nanosheets in a simple solvent process. The unique 1D PCBM nanostructures exhibit uniform width of 3.8 +/- 0.3 nm, equivalent to four PCBM molecules, and lengths of 20-400 nm. These nanoribbons show well-defined crystalline structure, comprising PCBM molecules in a hexagonal arrangement without trapped solvent molecules. First-principle calculations and detailed experimental characterization provide an insight into the structure and formation mechanism of the 1D PCBM nanoribbons. Given their dimensions and physical properties, we foresee that these nanostructures should be ideal as acceptor material in organic solar cells.
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| 9. |
- Kim, Y, et al.
(author)
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Nanomagnetic shielding : High-resolution NMR in carbon allotropes
- 2010
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In: Journal of Chemical Physics. - : American Institute of Physics. - 0021-9606 .- 1089-7690. ; 132, s. 021102-
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Journal article (peer-reviewed)abstract
- Theunderstanding and control of the magnetic properties of carbon-based materialsis of fundamental relevance in applications in nano- and biosciences.Ring currents do play a basic role in those systems.In particular the inner cavities of nanotubes offer an idealenvironment to investigate the magnetism of synthetic materials at thenanoscale. Here, by means of 13C high resolution NMR ofencapsulated molecules in peapod hybrid materials, we report the largestdiamagnetic shifts (down to −68.3 ppm) ever observed in carbonallotropes, which is connected to the enhancement of the aromaticityof the nanotube envelope upon doping. This diamagnetic shift canbe externally controlled by in situ modifications such as dopingor electrostatic charging. Moreover, defects such as C-vacancies, pentagons, andchemical functionalization of the outer nanotube quench this diamagnetic effectand restore NMR signatures to slightly paramagnetic shifts compared tononencapsulated molecules. The magnetic interactions reported here are robust phenomenaindependent of temperature and proportional to the applied magnetic field.The magnitude, tunability, and stability of the magnetic effects makethe peapod nanomaterials potentially valuable for nanomagnetic shielding in nanoelectronicsand nanobiomedical engineering
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| 10. |
- Sharifi, Tiva, et al.
(author)
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Graphene as an electrochemical transfer layer
- 2019
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In: Carbon. - : Elsevier. - 0008-6223 .- 1873-3891. ; 141, s. 266-273
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Journal article (peer-reviewed)abstract
- The capability of graphene to adopt a property from an adjacent material is investigated by measuring the electrochemical performance of a monolayer graphene placed on top of thin cobalt oxide (Co3O4) nanosheets. In this assembly, monolayer graphene works as an interfacial layer which inhibits the direct contact of the actual electroactive material and electrolyte during electrochemical reaction. The results show that while graphene is electrochemically inert, it behaves as an active material to catalyze oxygen evolution reaction (OER) once placed on top of Co3O4 nanosheets. The graphene-covered Co3O4 model system shows electrochemical performance similar to Co3O4 indicating complete transference of the electrochemical property of the metal oxide to the graphene. Based on density functional theory (DFT) calculations, charge transfer from graphene to Co3O4 is the key factor for turning the electrochemically inactive graphene to an apparent active material.
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| 11. |
- Zhang, Ying, et al.
(author)
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Capture of novel sp3 hybridized Z-BN by compressing boron nitride nanotubes with small diameter
- 2022
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In: Diamond and related materials. - : Elsevier. - 0925-9635 .- 1879-0062. ; 130
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Journal article (peer-reviewed)abstract
- Experimental synthesis of new sp3 hybridized carbon/boron nitride structures remains challenging despite that numerous sp3 structures have been proposed in theory. Here, we showed that compressed multi-walled boron nitride nanotubes (MWBNNTs) and boron nitride peapods (C60@BNNTs) with small diameters could transform into a new sp3 hybridized boron nitride allotrope (Z-BN). This strategy is considered from the topological transition point of view in boron nitride nanotubes upon compression. Due to the increased curvature in compressed small-diameter MWBNNTs, the uncommon 4- and 8-membered rings in Z-BN could be more favorably formed. And the irreversible tube collapse is proved to be a critical factor for the capture of the formed Z-BN, because of the competition between the resilience of tube before collapse and the stress limitation for the lattice stabilization of Z-BN upon decompression. In this case, Z-BN starts to form above 19.0 GPa, which is fully reversible below 45 GPa and finally becomes quenchable at 93.5 GPa. This collapse-induced capture of the high-pressure phase could also be extended to other tubular materials for quenching novel sp3 structures.
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