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| 2. |
- Dubrovina, L., et al.
(författare)
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One-pot synthesis of carbon nanotubes from renewable resource: cellulose acetate
- 2014
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Ingår i: Journal of Materials Science. - : Springer Science and Business Media LLC. - 0022-2461 .- 1573-4803. ; 49:3, s. 1144-1149
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Tidskriftsartikel (refereegranskat)abstract
- In the present work, we report for the first time one-pot synthesis of carbon nanotubes (CNTs) by pyrolysis of cellulose acetate (CA) cross-linked with polyisocyanate in the fumed silica template. NiCl2 was chosen as precatalyst for CNT growth. The diameter of CNTs is 24-38 nm and their wall thickness is 9-11 nm. The main role in the formation of CNTs by the pyrolysis of CA may be attributed to combination of closed macropores in the template formed by evolved CO2 during cross-linking reaction and mesopores formed by silica particles. The macropores acted as microreactors while the mesopores templated catalytic nanoparticles. The importance of this method for CNT synthesis reported here consists of the utilization of readily available renewable resource-CA. Moreover the method does not require preliminary synthesis of catalyst, it is technologically simple (can be performed in the conventional tube furnace), and hence it is energetically efficient.
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| 3. |
- Farjana, Sadia, 1983, et al.
(författare)
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Conductivity-Dependent Strain Response of Carbon Nanotube Treated Bacterial Nanocellulose
- 2013
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Ingår i: Journal of Sensors. - : Hindawi Limited. - 1687-7268 .- 1687-725X.
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports the strain sensitivity of flexible, electrically conductive, and nanostructured cellulose which was prepared by modification of bacterial cellulose with double-walled carbon nanotubes (DWCNTs) and multiwalled carbon nanotubes (MWCNTs). The electrical conductivity depends on the modifying agent and its dispersion process. The conductivity of the samples obtained from bacterial cellulose (BNC) pellicles modified with DWCNT was in the range from 0.034 S·cm−1 to 0.39 S·cm−1, and for BNC pellicles modified with MWCNTs it was from 0.12 S·cm−1 to 1.6 S·cm−1. The strain-induced electromechanical response, resistance versus strain, was monitored during the application of tensile force in order to study the sensitivity of the modified nanocellulose. A maximum gauge factor of 252 was found from the highest conductive sample treated by MWCNT. It has been observed that the sensitivity of the sample depends on the conductivity of the modified cellulose.
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| 4. |
- Kuzmenko, Volodymyr, 1987, et al.
(författare)
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Ammonium chloride promoted synthesis of carbon nanofibers from electrospun cellulose acetate
- 2014
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Ingår i: Carbon. - : Elsevier BV. - 0008-6223. ; 67, s. 694-703
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Tidskriftsartikel (refereegranskat)abstract
- Nitrogen-doped carbon nanofibrous mats with the fiber diameters between 70 and 400 nm were synthesized from regenerated cellulose impregnated with ammonium chloride. Acting as a flame retardant, ammonium chloride provided the thermal stabilization of incompletely regenerated cellulose fibers, thus allowing their successful carbonization. Besides that, it improved the carbon yield from 13% to 20%. The method of carbon nanofibers (CNF) synthesis reported here is technologically simple and environmentally friendly since it significantly shortens the regeneration step and does not require water consumption for washing of the precursor fibers from deacetylation agents. More than that, introduction of nitrogen via NH4Cl impregnation led to an increase in the electrical conductivity of the obtained CNF samples, a fact which can make them useful for advanced electrochemical applications.
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| 5. |
- Kuzmenko, Volodymyr, 1987, et al.
(författare)
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Capacitive effects of nitrogen doping on cellulose-derived carbon nanofibers
- 2015
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Ingår i: Materials Chemistry and Physics. - : Elsevier BV. - 0254-0584. ; 160, s. 59-65
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Tidskriftsartikel (refereegranskat)abstract
- Carbons with valuable electrochemical characteristics are among the most convenient electrode materials used for energy storage. At the moment, their production is mostly reliant on unsustainable fossil fuels. A preferential sustainable production of enhanced carbonaceous electrodes can be achieved with more extensive utilization of abundant renewable resources instead of fossils. In this study, nitrogen-doped carbon nanofibers (CNFs) were synthesized from cellulose, the most abundant renewable resource, via consecutive steps of cellulose acetate electrospinning, subsequent deacetylation to cellulose, impregnation with nitrogen-containing additive (ammonium chloride), and carbonization. Results of material characterization showed that the carbonization of functionalized cellulose samples led to formation of CNFs doped with 4–5.6 at.% of nitrogen. In comparison with pristine CNFs N-doped samples had a slightly lower specific surface area, but higher conductivity and hydrophilicity. Moreover, electrochemical measurements indicated that the enhanced N-doped materials had about 2.5 times higher specific capacitance which was increasing throughout 1000 charge–discharge cycles. These results suggest that nitrogen doping method used in this study has a positive pseudocapacitive effect on the electrochemical performance of carbonized cellulose materials.
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| 6. |
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| 7. |
- Kuzmenko, Volodymyr, 1987, et al.
(författare)
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Carbon nanotubes/nanofibers composites from cellulose for supercapacitors
- 2014
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Ingår i: 16th European Conference on Composite Materials, ECCM 2014; Seville; Spain; 22 June 2014 through 26 June 2014.
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Konferensbidrag (refereegranskat)abstract
- Cellulose-based carbon nanofibers (CNFs) with high mechanical strength and electrochemical stability were nitrogen-doped and functionalized with carbon nanotubes (CNTs) via two different methods. The diameter of incorporated CNTs was in the range of 1-20 nm. The doping with nitrogen atoms and incorporation of CNTs into the CNFs improved conductivity, while CNTs also increased surface area of the produced material. As a result, the composite materials with capacitance values up to 241 F/g were obtained.
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| 8. |
- Kuzmenko, Volodymyr, 1987, et al.
(författare)
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Cellulose-derived carbon nanofibers/graphene composite electrodes for powerful compact supercapacitors
- 2017
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 7:73, s. 45968-45977
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Tidskriftsartikel (refereegranskat)abstract
- Herein, we demonstrate a unique supercapacitor composite electrode material that is originated from a sustainable cellulosic precursor via simultaneous one-step carbonization/reduction of cellulose/graphene oxide mats at 800 degrees C. The resulting freestanding material consists of mechanically stable carbon nanofibrous (CNF, fiber diameter 50-500 nm) scaffolds tightly intertwined with highly conductive reduced graphene oxide (rGO) sheets with a thickness of 1-3 nm. The material is mesoporous and has electrical conductivity of 49 S cm(-1), attributed to the well-interconnected graphene layers. The electrochemical evaluation of the CNF/graphene composite electrodes in a supercapacitor device shows very promising volumetric values of capacitance, energy and power density (up to 46 F cm(-3), 1.46 W h L-1 and 1.09 kW L-1, respectively). Moreover, the composite electrodes retain an impressive 97% of the initial capacitance over 4000 cycles. With these superior properties, the produced composite electrodes should be the "looked-for" components in compact supercapacitors used for increasingly popular portable electronics and hybrid vehicles.
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| 9. |
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| 10. |
- Kuzmenko, Volodymyr, 1987, et al.
(författare)
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Functional cellulose-derived materials for energy storage
- 2014
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Ingår i: The 247th ACS National Meeting & Exposition, March 16-20, Dallas, TX, USA. ; 247
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Konferensbidrag (refereegranskat)abstract
- The biopolymer cellulose is an inexhaustible source for the synthesis of various functional materials for energy storage. It should be accounted as an alternative to the currently most used precursors (coal tar pitch and synthetic polymers) of carbon nanostructures. In this work, cellulose-based carbon nanofibers (CNF) with high mechanical strength and electrochemical stability were nitrogen-doped and functionalized with carbon nanotubes (CNT) via two different methods in order to obtain electrode materials for energy storage devices.Amorphous granular carbon nanofibers were produced by three consecutive steps of cellulose acetate electrospinning, cellulose regeneration and carbonization. Carbonization of pure cellulose samples resulted in the formation of 25-40 μm thick carbon sheets consisting of fibers with 20-180 nm diameter, and electrical capacitance of 10.8±0.5 F/g. Functionalization of CNF led to the composite materials with higher capacitance values. Impregnation of cellulose samples with NH4Cl before carbonization allowed obtaining N-doped CNF with higher carbon yield and electrical capacitance of 20.0±0.5 F/g. Impregnation of cellulose with double-walled CNT before carbonization resulted in CNF/CNT composite material with the capacitance of 34.9±0.5 F/g, and CNF covered with CNT deposited by chemical vapor after carbonization resulted in the composite material with the capacitance of 38.4±0.5 F/g. As a conclusion, functional cellulose-based materials are prospective electrode materials for energy storage devices.
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