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Barzegar, Hamid RezaORCID iD iconorcid.org/0000-0002-1314-5407
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Publications (10 of 27) Show all publications
Sharifi, T., Xie, Y., Zhang, X., Barzegar, H. R., Lei, J., Coulter, G., . . . Ajayan, P. M. (2019). Graphene as an electrochemical transfer layer. Carbon, 141, 266-273
Open this publication in new window or tab >>Graphene as an electrochemical transfer layer
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2019 (English)In: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 141, p. 266-273Article in journal (Refereed) Published
Abstract [en]

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. 

Place, publisher, year, edition, pages
Elsevier, 2019
National Category
Materials Chemistry
Identifiers
urn:nbn:se:umu:diva-154021 (URN)10.1016/j.carbon.2018.09.056 (DOI)000450312600029 ()
Funder
Swedish Research Council, 2015-06462Swedish Research Council, 2015-00520
Available from: 2018-12-20 Created: 2018-12-20 Last updated: 2018-12-20Bibliographically approved
Gracia-Espino, E., Barzegar, H. R. & Zettl, A. (2018). Coronene-based graphene nanoribbons insulated by boron nitride nanotubes: electronic properties of the hybrid structure. ACS Omega, 3(10), 12930-12935
Open this publication in new window or tab >>Coronene-based graphene nanoribbons insulated by boron nitride nanotubes: electronic properties of the hybrid structure
2018 (English)In: ACS Omega, ISSN 2470-1343, Vol. 3, no 10, p. 12930-12935Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:umu:diva-153661 (URN)10.1021/acsomega.8b01617 (DOI)000449026500069 ()
Funder
Carl Tryggers foundation , CTS-16-161Swedish Research Council, 2015-00520
Available from: 2018-11-26 Created: 2018-11-26 Last updated: 2018-11-26Bibliographically approved
Barzegar, H. R., Larsen, C., Boulanger, N., Zettl, A., Edman, L. & Wågberg, T. (2018). Self-assembled PCBM nanosheets: a facile route to electronic layer-on-Layer heterostructures. Nano letters (Print), 18(2), 1442-1447
Open this publication in new window or tab >>Self-assembled PCBM nanosheets: a facile route to electronic layer-on-Layer heterostructures
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2018 (English)In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 18, no 2, p. 1442-1447Article in journal, Editorial material (Refereed) Published
Abstract [en]

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.

Keywords
Organic electronic; organic heterostructures; PCBM nanosheets; self-assembly
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:umu:diva-144566 (URN)10.1021/acs.nanolett.7b05205 (DOI)000425559700114 ()29364679 (PubMedID)
Available from: 2018-02-06 Created: 2018-02-06 Last updated: 2018-06-13Bibliographically approved
Dunn, G., Shen, K., Barzegar, H. R., Shi, W., Belling, J. N., Nguyen, T. N. .., . . . Zettl, A. (2017). Selective Insulation of Carbon nanotubes. Physica status solidi. B, Basic research, 254(11), Article ID 1700202.
Open this publication in new window or tab >>Selective Insulation of Carbon nanotubes
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2017 (English)In: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 254, no 11, article id 1700202Article in journal, Editorial material (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2017
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:umu:diva-144557 (URN)10.1002/pssb.201700202 (DOI)000417609800005 ()
Available from: 2018-02-06 Created: 2018-02-06 Last updated: 2019-11-21Bibliographically approved
Barzegar, H. R., Yan, A., Coh, S., Gracia-Espino, E., Ojeda-Aristizabal, C., Dunn, G., . . . Zettl, A. (2017). Spontaneous twisting of a collapsed carbon nanotube. Nano Reseach, 10(6), 1942-1949
Open this publication in new window or tab >>Spontaneous twisting of a collapsed carbon nanotube
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2017 (English)In: Nano Reseach, ISSN 1998-0124, E-ISSN 1998-0000, Vol. 10, no 6, p. 1942-1949Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Tsinghua University Press, 2017
Keywords
multi-walled carbon nanotube, collapsed carbon nanotube, in situ TEM, electron diffraction, twisting, graphene nanoribbons
National Category
Biochemicals Composite Science and Engineering
Identifiers
urn:nbn:se:umu:diva-136050 (URN)10.1007/s12274-016-1380-7 (DOI)000401320700010 ()
Available from: 2017-06-20 Created: 2017-06-20 Last updated: 2018-06-09Bibliographically approved
Iqbal, J., Enevold, J., Larsen, C., Wang, J., Revoju, S., Barzegar, H. R., . . . Edman, L. (2016). An arylene-vinylene based donor-acceptor-donor small molecule for the donor compound in high-voltage organic solar cells. Solar Energy Materials and Solar Cells, 155, 348-355
Open this publication in new window or tab >>An arylene-vinylene based donor-acceptor-donor small molecule for the donor compound in high-voltage organic solar cells
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2016 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 155, p. 348-355Article in journal (Refereed) Published
Abstract [en]

A donor-acceptor-donor (D-A-D) molecule has been designed and synthesized for use as the electron donating material in solution-processed small-molecule organic solar cells (OSCs). The D-A-D molecule comprises a central electron-accepting (2Z,2'Z)-2,2'-(2,5-bis(octyloxy)-1,4-phenylene)bis(3-(thiophen-2-yl)acry lonitrile) (ZOPTAN) core, which is chemically connected to two peripheral and electron-donating triphenylamine (TPA) units. The ZOPTAN-TPA molecule features a low HOMO level of -5.2 eV and an optical energy gap of 2.1 eV. Champion OSCs based on a solution-processed and non-annealed active material blend of [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM) and ZOPTAN-TPA in a mass ratio of 2:1 exhibits a power conversion efficiency of 1.9% and a high open-circuit voltage of 1.0 V. 

Keywords
Organic solar cell, Small-molecule donor, Fullerene acceptor, Solution processing, High open-circuit ltage, Thermal stability
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-126290 (URN)10.1016/j.solmat.2016.06.018 (DOI)000381529100040 ()
Available from: 2016-11-08 Created: 2016-10-03 Last updated: 2018-06-09Bibliographically approved
Barzegar, H. R., Yan, A., Coh, S., Gracia-Espino, E., Dunn, G., Wågberg, T., . . . Zettl, A. (2016). Electrostatically Driven Nanoballoon Actuator [Letter to the editor]. Nano letters (Print), 16(11), 6787-6791
Open this publication in new window or tab >>Electrostatically Driven Nanoballoon Actuator
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2016 (English)In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 16, no 11, p. 6787-6791Article in journal, Letter (Refereed) Published
Abstract [en]

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.

Keywords
Nanoballoon, actuator, collapsed carbon nanotube, nanomanipulator, reinflation
National Category
Condensed Matter Physics Nano Technology
Identifiers
urn:nbn:se:umu:diva-129209 (URN)10.1021/acs.nanolett.6b02394 (DOI)000387625000011 ()
Available from: 2016-12-22 Created: 2016-12-21 Last updated: 2018-06-09Bibliographically approved
Barzegar, H. R., Pham, T., Talyzin, A. V. & Zettl, A. (2016). Synthesis of graphene nanoribbons inside boron nitride nanotubes. Physica status solidi. B, Basic research, 253(12), 2377-2379
Open this publication in new window or tab >>Synthesis of graphene nanoribbons inside boron nitride nanotubes
2016 (English)In: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 253, no 12, p. 2377-2379Article in journal (Refereed) Published
Abstract [en]

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.

Keywords
boron nitride nanotubes, coronene, graphene nanoribbons
National Category
Nano Technology Condensed Matter Physics
Identifiers
urn:nbn:se:umu:diva-130246 (URN)10.1002/pssb.201600294 (DOI)000390339000015 ()
Available from: 2017-01-16 Created: 2017-01-14 Last updated: 2018-06-09Bibliographically approved
Barzegar, H. R., Gracia Espino, E. & Wågberg, T. (2015). C60/Collapsed Carbon Nanotube Hybrids: A Variant of Peapods [Letter to the editor]. Nano letters (Print), 15(2), 829-834
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, p. 829-834Article 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.

Keywords
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: 2018-06-13Bibliographically approved
Gracia-Espino, E., Barzegar, H. R., Sharifi, T., Yan, A., Zettl, A. & Wågberg, T. (2015). Fabrication of One-Dimensional Zigzag [6,6]-Phenyl-C-61-Butyric Acid Methyl Ester Nanoribbons from Two-Dimensional Nanosheets. ACS Nano, 9(10), 10516-10522
Open this publication in new window or tab >>Fabrication of One-Dimensional Zigzag [6,6]-Phenyl-C-61-Butyric Acid Methyl Ester Nanoribbons from Two-Dimensional Nanosheets
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2015 (English)In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 9, no 10, p. 10516-10522Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2015
Keywords
PCBM, nanosheets, nanoribbons, nanorods, liquid-liquid interfacial precipitation, electron croscopy, density functional theory calculations
National Category
Physical Chemistry Nano Technology
Identifiers
urn:nbn:se:umu:diva-112014 (URN)10.1021/acsnano.5b04972 (DOI)000363915300107 ()26381227 (PubMedID)
Available from: 2015-11-30 Created: 2015-11-30 Last updated: 2018-06-07Bibliographically approved
Projects
Nano-cavity for encapsulation of small molecules; towards synthesis of one-dimensional hybrid structures and liquid cell for electron microscopy [2015-00520_VR]; Umeå University
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-1314-5407

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