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Publications (10 of 53) Show all publications
Song, M., Tahershamsi, L., Zhao, J., Zhang, Z.-B. & Grennberg, H. (2018). Efficient Gelation of Graphene Oxide Aqueous Dispersion Induced by Sonication-Promoted Leuckart Reaction. ChemNanoMat, 4(11), 1145-1152
Open this publication in new window or tab >>Efficient Gelation of Graphene Oxide Aqueous Dispersion Induced by Sonication-Promoted Leuckart Reaction
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2018 (English)In: ChemNanoMat, ISSN 2199-692X, Vol. 4, no 11, p. 1145-1152Article in journal (Refereed) Published
Abstract [en]

Abstract Graphene oxide (GO) undergoes a rapid gelation process in the presence of ammonium hydroxide and formic acid at room temperature which is promoted by ultrasonication. Infrared and X-ray photoelectron spectroscopy proved partial reduction of GO and nitrogen incorporation, resulting from sonication-promoted Leuckart reactions at GO carbonyl groups. The amine groups produced via Leuckart reactions undergo further reactions that result in salt bridges with carboxylic groups and covalent cross-links, both of which contribute to the stabilization of the resulting hydrogel. The resultant GO hydrogel exhibits enhanced thermal stability.

Keywords
Gelation, graphene oxide, hydrogels, Leuckart reaction, ultrasonication
National Category
Materials Engineering
Identifiers
urn:nbn:se:uu:diva-363972 (URN)10.1002/cnma.201800286 (DOI)000452398900006 ()
Funder
Swedish Foundation for Strategic Research , SE13-0061Swedish Research Council, No. 621-2014-5596Knut and Alice Wallenberg Foundation
Available from: 2018-10-22 Created: 2018-10-22 Last updated: 2019-02-25
Song, M., Zhao, J., Grennberg, H. & Zhang, Z.-B. (2018). Screen Printed Conductive Composites with Reduced Graphene Oxide and Silver. In: 2018 IMAPS Nordic Conference on Microelectronics Packaging (NordPac): . Paper presented at 2018 IMAPS Nordic Conference on Microelectronics Packaging (NordPac), 12th – 14th June 2018, Oulu, Finland (pp. 35-39).
Open this publication in new window or tab >>Screen Printed Conductive Composites with Reduced Graphene Oxide and Silver
2018 (English)In: 2018 IMAPS Nordic Conference on Microelectronics Packaging (NordPac), 2018, p. 35-39Conference paper, Published paper (Refereed)
Abstract [en]

This work provides a method to fabricate conductive composites by screen printing of aqueous hybrid inks with graphene oxide (GO) and silver acetate as silver source. The formulation of the aqueous hybrid inks is realized by mixing highly concentrated GO solution and reactive silver solution, which readily results in a formation of viscous pastes. Composite films with four-probe structure were fabricated by means of blade coating, followed by annealing at 160 °C in air and subsequently at 600 °C in Ar/H 2 . While the reactive silver solution without GO can be completely reduced when annealed at 90 °C in air, resulting in elemental Ag films with resistivity close to the bulk value, no reduction occurs in the hybrid inks under the same annealing condition. Silver nanoparticles are formed from the hybrid inks at 160 °C and discretely distributed on the reduced GOs (rGOs), which shows a retardation effect of GO on the reduction of silver. Further annealing at 600 °C in Ar/H 2 leads to partial restoration of sp 2 lattice in the rGOs. The resistivity of the composite films increases as the silver content is increased, which is interpreted by using a percolation model with rGO networks.

Keywords
annealing, coatings, electrical conductivity, electrical resistivity, graphene compounds, mixing, nanocomposites, nanofabrication, nanoparticles, percolation, reduction (chemical), silver, thin films, aqueous hybrid inks, silver acetate, reactive silver solution, silver nanoparticles, reduced graphene oxide, screen printed conductive composites, viscous pastes, four-probe structure, blade coating, retardation effect, percolation model, temperature 160.0 degC, temperature 600.0 degC, temperature 90.0 degC, CO-Ag, Ink, Films, Conductivity, Printing, Graphene, graphene oxide, conductive composite, screen printing
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-363974 (URN)10.23919/NORDPAC.2018.8423856 (DOI)
Conference
2018 IMAPS Nordic Conference on Microelectronics Packaging (NordPac), 12th – 14th June 2018, Oulu, Finland
Funder
Swedish Research Council, No. 621-2014-5596Swedish Foundation for Strategic Research , Dnr SE13-0061
Available from: 2018-10-22 Created: 2018-10-22 Last updated: 2019-03-14Bibliographically approved
Lundstedt, A., Webb, M. J. & Grennberg, H. (2017). Ozonolysis of polycyclic aromatic hydrocarbons in participating solvents. RSC Advances, 7(10), 6152-6159
Open this publication in new window or tab >>Ozonolysis of polycyclic aromatic hydrocarbons in participating solvents
2017 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, no 10, p. 6152-6159Article in journal (Refereed) Published
Abstract [en]

Seven polycyclic aromatic hydrocarbon (PAH) compounds that can be considered small models for graphene edges have been treated with ozone in solution. The presence of participating solvents such as water or methanol had a pronounced influence on conversion and identity of the functional groups formed, whereas the regioselectivity of the ozonation remained unaffected. Six previously unreported compounds have been isolated from the ozonolysis of pyrene 1, perylene 2 and benzo[e] pyrene 4. Comparison of the experimental data with calculated local ionization energy surfaces (IES) shows a good correlation, and indicates that this computational tool would be useful to predict the regioselectivity of ozone also for larger PAHs, including graphene and graphene nanoribbons.

National Category
Organic Chemistry
Identifiers
urn:nbn:se:uu:diva-316964 (URN)10.1039/c6ra26248a (DOI)000393754100073 ()
Funder
Swedish Research CouncilKnut and Alice Wallenberg Foundation
Available from: 2017-03-08 Created: 2017-03-08 Last updated: 2017-11-29Bibliographically approved
Lundstedt, A., Papadakis, R., Li, H., Han, Y., Bergman, J., Leifer, K., . . . Ottosson, H. (2017). White-light photoassisted covalent functionalization of graphene using 2-propanol. Small Methods, 1(11), Article ID 1700214.
Open this publication in new window or tab >>White-light photoassisted covalent functionalization of graphene using 2-propanol
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2017 (English)In: Small Methods, ISSN 2366-9608, Vol. 1, no 11, article id 1700214Article in journal (Refereed) Published
Abstract [en]

Herein, a photochemical method for functionalization of graphene using 2-propanol is reported. The functionalization method which is catalyst-free operates at ambient temperature in neat 2-propanol under an inert atmosphere of argon. The equipment requirement is a white-light source for the irradiation. The same methodology when applied to kish graphite results in a novel material, exhibiting significantly higher wettability than the starting material according to water contact angle measurements. Furthermore, the materials generated from both graphene and kish graphite exhibit increased adhesion energy, attributed to the fixation of isopropyl alcohol fragments onto graphene and graphite, respectively. The presence of hydroxyl groups and the possibility for further reactions on the functionalized graphene material are demonstrated through a substitution reaction with thionyl chloride, where the hydroxyl groups are replaced with chlorides, as confirmed through X-ray photoelectron spectroscopy analysis.

Place, publisher, year, edition, pages
John Wiley & Sons, 2017
National Category
Materials Engineering Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-314171 (URN)10.1002/smtd.201700214 (DOI)000417488900006 ()
Funder
Wenner-Gren FoundationsSwedish Research CouncilKnut and Alice Wallenberg FoundationÅForsk (Ångpanneföreningen's Foundation for Research and Development)Magnus Bergvall Foundation
Available from: 2017-01-29 Created: 2017-01-29 Last updated: 2019-04-24Bibliographically approved
Nordlund, M., Kazen Orrefur, J. & Grennberg, H. (2016). Functionalization of fullerenes via metal catalyzed hydroarylation. In: : . Paper presented at Organikerdagarna, Umeå, juni 2016.
Open this publication in new window or tab >>Functionalization of fullerenes via metal catalyzed hydroarylation
2016 (English)Conference paper, Oral presentation with published abstract (Refereed)
National Category
Organic Chemistry
Identifiers
urn:nbn:se:uu:diva-354860 (URN)
Conference
Organikerdagarna, Umeå, juni 2016
Available from: 2018-06-23 Created: 2018-06-23 Last updated: 2018-10-31Bibliographically approved
Nordlund, M., Bhandary, S., Sanyal, B., Almqvist, N., Löfqvist, T. & Grennberg, H. (2016). Side-selective self-assembly of graphene and FLG on piezoelectric PVDF from suspension. Journal of Physics D: Applied Physics, 49(7), Article ID 07LT01.
Open this publication in new window or tab >>Side-selective self-assembly of graphene and FLG on piezoelectric PVDF from suspension
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2016 (English)In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 49, no 7, article id 07LT01Article in journal (Refereed) Published
Abstract [en]

The deposition of few-layer graphene by self-assembly from suspension onto a piezoelectric polymer substrate is presented. The graphene self-assembles with negligible overlap between flakes, and with high selectivity for one of the faces of the substrate, an observation which is discussed and rationalized. A computational study on a model system further confirms the theory and supports the experimental results. The highest obtained degree of surface coverage was estimated to 77%.

Keywords
graphene, PVDF, self-assembly, selective, deposition
National Category
Organic Chemistry Other Physics Topics Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-276051 (URN)10.1088/0022-3727/49/7/07LT01 (DOI)000369403700001 ()
Funder
Swedish Research CouncilKnut and Alice Wallenberg FoundationThe Kempe Foundations
Available from: 2016-02-09 Created: 2016-02-09 Last updated: 2017-11-30Bibliographically approved
Blom, M., Norrehed, S., Andersson, C.-H., Huang, H., Light, M. E., Bergquist, J., . . . Gogoll, A. (2016). Synthesis and Properties of Bis-Porphyrin Molecular Tweezers: Effects of Spacer Flexibility on Binding and Supramolecular Chirogenesis. Molecules, 21(1)
Open this publication in new window or tab >>Synthesis and Properties of Bis-Porphyrin Molecular Tweezers: Effects of Spacer Flexibility on Binding and Supramolecular Chirogenesis
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2016 (English)In: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 21, no 1Article in journal (Refereed) Published
Abstract [en]

Abstract: Ditopic binding of various dinitrogen compounds to three bisporphyrin molecular tweezers with spacers of varying conformational rigidity, incorporating the planar ene-diyne (1), the helical stiff stilbene (2), or the semirigid glycoluril motif fused to  the porphyrins (3) are compared. Binding constants Ka = 10^4 to 10^6 M^-1 reveal subtle  differences between these tweezers, that are discussed in terms of porphyrin dislocation  modes. Exciton coupled circular dichroism (ECCD) of complexes with chiral dinitrogen  guests provides experimental evidence for the conformational properties of the tweezers. The results are further supported and rationalized by conformational analysis.

Keywords
Bisporphyrin tweezers, metalloporphyrins, porphyrinoids, host-guest chemistry, supramolecular chemistry, chirogenesis, chirality transfer, exciton coupled circular dichroism, conformational analysis
National Category
Organic Chemistry Engineering and Technology
Research subject
Chemistry with specialization in Organic Chemistry; Engineering Science with specialization in Nanotechnology and Functional Materials
Identifiers
urn:nbn:se:uu:diva-267826 (URN)10.3390/molecules21010016 (DOI)000369485600001 ()
Funder
Swedish Research Council, 621-2012-3379Swedish Research Council, 621-2011-4423
Available from: 2015-11-27 Created: 2015-11-27 Last updated: 2017-12-01Bibliographically approved
Yager, T., Webb, M. J., Grennberg, H., Yakimova, R., Lara-Avila, S. & Kubatkin, S. (2015). High mobility epitaxial graphene devices via aqueous-ozone processing. Applied Physics Letters, 106(6), Article ID 063503.
Open this publication in new window or tab >>High mobility epitaxial graphene devices via aqueous-ozone processing
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2015 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 106, no 6, article id 063503Article in journal (Refereed) Published
Abstract [en]

We find that monolayer epitaxial graphene devices exposed to aggressive aqueous-ozone processing and annealing became cleaner from post-fabrication organic resist residuals and, significantly, maintain their high carrier mobility. Additionally, we observe a decrease in carrier density from inherent strong n-type doping to extremely low p-type doping after processing. This transition is explained to be a consequence of the cleaning effect of aqueous-ozone processing and annealing, since the observed removal of resist residuals from SiC/G enables the exposure of the bare graphene to dopants present in ambient conditions. The resulting combination of charge neutrality, high mobility, large area clean surfaces, and susceptibility to environmental species suggest this processed graphene system as an ideal candidate for gas sensing applications. (C) 2015 AIP Publishing LLC.

National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:uu:diva-248460 (URN)10.1063/1.4907947 (DOI)000349845300075 ()
Available from: 2015-03-31 Created: 2015-03-30 Last updated: 2017-12-04Bibliographically approved
Eriksson, S. K., Hahlin, M., Kahk, J. M., Villar-Garcia, I. J., Webb, M. J., Grennberg, H., . . . Payne, D. J. (2014). A versatile photoelectron spectrometer for pressures up to 30 mbar. Review of Scientific Instruments, 85(7), 075119
Open this publication in new window or tab >>A versatile photoelectron spectrometer for pressures up to 30 mbar
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2014 (English)In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 85, no 7, p. 075119-Article in journal (Refereed) Published
Abstract [en]

High-pressure photoelectron spectroscopy is a rapidly developing technique with applications in a wide range of fields ranging from fundamental surface science and catalysis to energy materials, environmental science, and biology. At present the majority of the high-pressure photoelectron spectrometers are situated at synchrotron end stations, but recently a small number of laboratory-based setups have also emerged. In this paper we discuss the design and performance of a new laboratory based high pressure photoelectron spectrometer equipped with an Al Kα X-ray anode and a hemispherical electron energy analyzer combined with a differentially pumped electrostatic lens. The instrument is demonstrated to be capable of measuring core level spectra at pressures up to 30 mbar. Moreover, valence band spectra of a silver sample as well as a carbon-coated surface (graphene) recorded under a 2 mbar nitrogen atmosphere are presented, demonstrating the versatility of this laboratory-based spectrometer.

National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-230851 (URN)10.1063/1.4890665 (DOI)000341176600066 ()25085185 (PubMedID)
Available from: 2014-08-31 Created: 2014-08-31 Last updated: 2017-12-30
Webb, M. J., Polley, C., Dirscherl, K., Burwell, G., Palmgren, P., Niu, Y., . . . Grennberg, H. (2014). Effects of a modular two-step ozone-water and annealing process on silicon carbide graphene. Applied Physics Letters, 105(8), 081602
Open this publication in new window or tab >>Effects of a modular two-step ozone-water and annealing process on silicon carbide graphene
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2014 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 105, no 8, p. 081602-Article in journal (Refereed) Published
Abstract [en]

By combining ozone and water, the effect of exposing epitaxial graphene on silicon carbide to an aggressive wet-chemical process has been evaluated after high temperature annealing in ultra high vacuum. The decomposition of ozone in water produces a number of oxidizing species, however, despite long exposure times to the aqueous-ozone environment, no graphene oxide was observed after the two-step process. The systems were comprehensively characterized before and after processing using Raman spectroscopy, core level photoemission spectroscopy, and angle resolved photoemission spectroscopy together with low energy electron diffraction, low energy electron microscopy, and atomic force microscopy. In spite of the chemical potential of the aqueous-ozone reaction environment, the graphene domains were largely unaffected raising the prospect of employing such simple chemical and annealing protocols to clean or prepare epitaxial graphene surfaces. (C) 2014 AIP Publishing LLC.

National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-236095 (URN)10.1063/1.4893781 (DOI)000342753500017 ()
External cooperation:
Available from: 2014-11-14 Created: 2014-11-12 Last updated: 2017-12-05Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-3223-5456

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