| 1. |
- Luzan, Serhiy, 1985-, et al.
(författare)
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Hydrogen adsorption in Pt catalyst/MOF-5 materials
- 2010
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Ingår i: Microporous and Mesoporous Materials. - : Elsevier. - 1387-1811 .- 1873-3093. ; 135:1-3, s. 201-205
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogen adsorption properties of well-known MOF-5 were studied at near ambient temperature and hydrogen pressures up to 120 bar. Pristine material was doped with Pt catalysts supported on activated carbon (AC) using two previously described procedures: physical mixture of a catalyst with MOF-5 and “bridging” procedure (MOF-5 and catalyst particles connected via carbon bridges) MOF-5. The maximum hydrogen adsorption measured on doped MOF-5 was 0.43 wt.%. These values are on the same level or even less than for catalyst free MOF-5 material. Therefore, doping of MOF-5 material with Pt catalyst has not resulted in increase of hydrogen storage value. Hydrogen adsorption for the samples with added catalyst showed correlation with BET surface area, exhibited isotherms typical for physisorption and no features which could be assigned to spillover effect.
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| 2. |
- Luzan, Serhiy, 1985-, et al.
(författare)
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Hydrogen storage in Co-and Zn-based metal-organic frameworks at ambient temperature
- 2009
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Ingår i: International journal of hydrogen energy. - : Elsevier. - 0360-3199 .- 1879-3487. ; 34:24, s. 9754-9759
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogen adsorption properties of some Co-and Zn-based Metal-Organic Framework (MOF) materials were studied at near ambient temperatures. Maximal hydrogen storage capacity of 0.75 wt% was found for a Zn-based material at 175 Bar hydrogen pressure and T = -4 degrees C. Hydrogen adsorption correlated linearly with BET surface area and strongly depends on temperature. Relatively low structural stability of some MOF's results in framework collapse during degassing and hydrogen adsorption measurements.
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| 3. |
- Luzan, Serhiy M, 1985-, et al.
(författare)
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Effect of catalysts on the reaction of C60 with hydrogen
- 2012
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Ingår i: Fullerenes, nanotubes, and carbon nanostructures. - : Taylor & Francis Group. - 1536-383X .- 1536-4046. ; 20:4-7, s. 319-323
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Tidskriftsartikel (refereegranskat)abstract
- The reaction of C-60/catalyst with hydrogen gas was studied at 400 degrees C and 50 bar of H-2 pressure. The addition of Pt- or Ni-catalysts significantly accelerated kinetics of the hydrogenation reaction and resulted in a dramatic change of the C60Hx crystal structure. Samples reacted without catalyst preserved the fcc structure typical for pristine C-60 but with expanded unit cells. Fulleranes C60Hx obtained using catalytic hydrogenation exhibited not only the fcc structure (at relatively low hydrogenation degree) but also the bcc structure of C60Hx (with x > 18). The bcc structure corresponds to highly hydrogenated material with an average volume per C-60 molecule of 817-849 angstrom(3).
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| 4. |
- Luzan, Serhiy, 1985-
(författare)
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Materials for Hydrogen storage and synthesis of new materials by hydrogenation
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The search for new materials for hydrogen storage is important for the development of future hydrogen energy applications. In this Thesis, it is shown that new materials with interesting properties can be synthesized by the reaction of hydrogen with various nanocarbon precursors. The thesis consists of two parts. The first part is devoted to studies of hydrogen storage in some metal-organic frameworks (MOFs) and nanostructured carbon materials, while the second part describes synthesis of new materials by the reaction of hydrogen gas with various carbon materials (i.e. fullerene C60, single-walled carbon nanotubes (SWCNTs), and fullerene C60 encapsulated inside SWCNTs (C60@SWCNTs)).Hydrogen adsorption was measured for a set of Zn- and Co-based MOFs at near ambient temperatures. MOFs synthesized using different metal clusters and organic connecting ligands allowed to study effects of different surface area, pore volume, and pore shapes on hydrogen storage parameters. Hydrogen adsorption values in the studied MOFs correlated well with surface area and pore volume but did not exceed 0,75wt.%. Therefore, new methods to improve the hydrogen storage capacity in MOFs were investigated. The addition of metal catalysts was previously reported to improve significantly hydrogen storage in MOFs. In this thesis the effect of Pt catalyst addition on hydrogen adsorption in MOF-5 was not confirmed. Contrary to previous reports, hydrogen adsorption in MOF-5 mixed/modified with Pt catalysts had fast kinetics, correlated well with surface area, and was on the same level as for unmodified MOF-5. New nanostructured carbon materials were synthesized by the reaction between fullerene C60 and coronene/anthracene. Despite negligible surface area these materials adsorbed up to 0,45wt.% of hydrogen at ambient temperatures.The reaction of fullerene C60 with hydrogen gas was studied at elevated temperatures and hydrogen pressures. In situ gravimetric monitoring of the reaction was performed in a broad temperature interval with/without addition of metal catalysts (i.e. Pt and Ni). The reaction resulted in synthesis of hydrogenated fullerenes C60Hx (with x≤56) followed by fullerene cage fragmentation and collapse upon prolonged duration of hydrogen treatment. Possible mechanisms of C60 hydrogenation and fragmentation were discussed. It is demonstrated that reaction of SWCNTs with hydrogen gas at elevated temperatures and hydrogen pressures can be used for nanotube opening, purification from amorphous carbon, side-wall hydrogenation, and partial unzipping of SWCNTs. Some graphene nanoribbons (GNRs) were synthesized as the result of SWCNTs unzipping. A surprising ability of hydrogen to penetrate inside SWNTs and to react with encapsulated fullerene C60 was demonstrated.
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| 5. |
- Luzan, Serhiy, 1985-, et al.
(författare)
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Reaction of C60 with Hydrogen gas : In Situ monitoring and pathways
- 2011
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 115:23, s. 11484-11492
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Tidskriftsartikel (refereegranskat)abstract
- Kinetics and pathways of C60 reaction with hydrogen gas were studied in a broad temperature interval and over extended periods of time. Specifically, hydrogenation was monitored in situ at high temperature and high hydrogen pressure conditions using the gravimetric method. The shape of gravimetric curve was found to depend on hydrogenation temperature: at 350–400 °C saturation of the sample weight was achieved, whereas at 420–440 °C the sample weight reached the maximum and decreased upon prolonged hydrogenation. The weight decrease is due to fullerene cage fragmentation with formation of light hydrocarbons evaporating from the sample. Hydrogenation products were studied by X-ray diffraction, MALDI TOF and APPI FT-ICR mass spectrometry, liquid chromatography, and elemental analysis. Hydrogenation pathways (from C60H18 up to C60H56) and possible mechanisms of hydrogenation-induced fragmentation of fulleranes are discussed.
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| 6. |
- Luzan, Serhiy, 1985-, et al.
(författare)
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Thermal decomposition of C60H18
- 2009
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 113:30, s. 13133-13138
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Tidskriftsartikel (refereegranskat)abstract
- Products of thermal dehydrogenation of C 60H18(which mainly occurs at 450-600°C) were studied by XRD, Raman, IR and mass spectrometry. IR spectra indicate that dehydrogenation resulted in partial recovery of pristine C 60. XRD data indicate that the cell parameter of the face-centered cubic structure, which is higher for C 60H18(14.55 Å) than for C60(14.17 Å), remained higher following heat treatment, and heating at>500° C caused further expansion (to 14.78 Å). The increase in the cell parameter correlates with the beginning of partial fullerene cage collapse (corroborated by IR, Raman and MS data) and is suggested to result from “self-doping”.
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| 7. |
- Martin, Natalia M., et al.
(författare)
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High-temperature reactions of C60 with polycyclic aromatic hydrocarbons
- 2010
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Ingår i: Chemical Physics. - : Elsevier. - 0301-0104 .- 1873-4421. ; 368:1-2, s. 49-57
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Tidskriftsartikel (refereegranskat)abstract
- Fullerenes are proposed as a precursor for preparation of nanocarbon materials using controlled collapse of cage structure by high temperature reaction with polycyclic aromatic hydrocarbons. The chemical modification of C60 by reaction with anthracene and coronene was studied over a broad temperature interval. The products of the reaction were characterized by X-ray diffraction, and Raman and IR spectroscopy. Mono- and multi-adducts of C60 with anthracene were obtained in the temperature interval 290–400 °C. Above 400 °C the C60 adducts are not stable and decompose back to C60 and anthracene. No chemical adducts of C60 with coronene were found below 500 °C. Above this temperature fullerite structure was found to expand reflecting interaction with coronene melt and vapor. The reactions of C60 with anthracene and C60 with coronene at temperatures above 650 °C resulted in fullerene cage collapse and formation of nanocarbons. These nanocarbons were found to store up to 0.45 wt% of hydrogen at ambient temperatures despite negligible surface area.
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| 8. |
- Talyzin, Alexandr, 1969-, et al.
(författare)
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Hydrogenation, Purification, and Unzipping of Carbon Nanotubes by Reaction with Molecular Hydrogen : Road to Graphane Nanoribbons
- 2011
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 5:6, s. 5132-5140
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Tidskriftsartikel (refereegranskat)abstract
- Reaction of single-walled carbon nanotubes (SWNTs) with hydrogen gas was studied in a temperature interval of 400-550 degrees C and at hydrogen pressure of 50 bar. Hydrogenation of nanotubes was observed for samples treated at 400-450 degrees C with about 1/3 of carbon atoms forming covalent C-H bonds, whereas hydrogen treatment at higher temperatures (550 degrees C) occurs as an etching. Unzipping of some SWNTs Into graphene nanoribbons is observed as a result of hydrogenation at 400-550 degrees C Annealing in hydrogen gas at elevated conditions for prolonged periods of time (72 h) is demonstrated to result also in nanotube opening, purification of nanotubes from amorphous carbon, and removal of carbon coatings from Fe catalyst particles, which allows their complete elimination by acid treatment.
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| 9. |
- Talyzin, Alexandr V., et al.
(författare)
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Hydrogen-Driven Cage Unzipping of C-60 into Nano-Graphenes
- 2014
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 118:12, s. 6504-6513
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Tidskriftsartikel (refereegranskat)abstract
- Annealing of C-60 in hydrogen at temperatures above the stability limit of C H bonds in C60Hx (500-550 degrees C) is found to result in direct collapse of the cage structure, evaporation of light hydrocarbons, and formation of solid mixture composed of larger hydrocarbons and few-layered graphene sheets. Only a minor part of this mixture is soluble; this was analyzed using matrix-assisted laser desorption/ionization MS, Fourier transform infrared (FTIR), and nuclear magnetic resonance spectroscopy and found to be a rather complex mixture of hydrocarbon molecules composed of at least tens of different compounds. The sequence of most abundant peaks observed in MS, which corresponds to C2H2 mass difference, suggests a stepwise breakup of the fullerene cage into progressively smaller molecular fragments edge-terminated by hydrogen. A simple model of hydrogen-driven C-60 unzipping is proposed to explain the observed sequence of fragmentation products. The insoluble part of the product mixture consists of large planar polycyclic aromatic hydrocarbons, as evidenced by FTIR and Raman spectroscopy, and some larger sheets composed of few-layered graphene, as observed by transmission electron microscopy. Hydrogen annealing of C-60 thin films showed a thickness-dependent results with reaction products significantly different for the thinnest films compared to bulk powders. Hydrogen annealing of C-60 films with the thickness below 10 nm was found to result in formation of nanosized islands with Raman spectra very similar to the spectra of coronene oligomers and conductivity typical for graphene.
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| 10. |
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