| 1. |
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| 2. |
- Dubrovina, L., et al.
(author)
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One-pot synthesis of carbon nanotubes from renewable resource: cellulose acetate
- 2014
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In: Journal of Materials Science. - : Springer Science and Business Media LLC. - 0022-2461 .- 1573-4803. ; 49:3, s. 1144-1149
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Journal article (peer-reviewed)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.
(author)
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Conductivity-Dependent Strain Response of Carbon Nanotube Treated Bacterial Nanocellulose
- 2013
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In: Journal of Sensors. - : Hindawi Limited. - 1687-7268 .- 1687-725X.
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Journal article (peer-reviewed)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.
(author)
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Ammonium chloride promoted synthesis of carbon nanofibers from electrospun cellulose acetate
- 2014
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In: Carbon. - : Elsevier BV. - 0008-6223. ; 67, s. 694-703
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Journal article (peer-reviewed)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.
(author)
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Capacitive effects of nitrogen doping on cellulose-derived carbon nanofibers
- 2015
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In: Materials Chemistry and Physics. - : Elsevier BV. - 0254-0584. ; 160, s. 59-65
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Journal article (peer-reviewed)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.
(author)
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Carbon nanotubes/nanofibers composites from cellulose for supercapacitors
- 2014
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In: 16th European Conference on Composite Materials, ECCM 2014; Seville; Spain; 22 June 2014 through 26 June 2014.
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Conference paper (peer-reviewed)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.
(author)
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Cellulose-derived carbon nanofibers/graphene composite electrodes for powerful compact supercapacitors
- 2017
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In: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 7:73, s. 45968-45977
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Journal article (peer-reviewed)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.
(author)
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Functional cellulose-derived materials for energy storage
- 2014
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In: The 247th ACS National Meeting & Exposition, March 16-20, Dallas, TX, USA. ; 247
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Conference paper (peer-reviewed)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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| 11. |
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| 12. |
- Kuzmenko, Volodymyr, 1987, et al.
(author)
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Sustainable carbon nanofibers/nanotubes composites from cellulose as electrodes for supercapacitors
- 2015
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In: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 90:2, s. 1490-1496
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Journal article (peer-reviewed)abstract
- Supercapacitors are efficient energy storage devices with long lifetime and safe service. Their effectiveness,to a big extent, is dependent on electrode materials used for accumulation of energy in form ofelectrostatic charges. Over the last decades, variety of carbonaceous electrode materials has been used insupercapacitors. Mostly the production of such electrodes is still oriented on unsustainable fossil fuels asprecursors instead of sustainable renewable resources. In this study, freestanding carbonaceous electrodematerials for supercapacitors were derived from cellulose, the most abundant renewable resource. Theywere synthesized via carbonization of fibrillar cellulose impregnated with CNTs (carbon nanotubes). Theensuing composite materials consisted of a CNF (carbon nanofiber) scaffold (fiber diameter in the rangeof 50-250 nm) covered with layers of CNTs (tube diameter in the range of 1-20 nm). Moreover, thesecomposites were tested as electrode materials for supercapacitors. Incorporation of the CNTs into theCNFs improved electrical conductivity and also increased the surface area of the produced compositematerials, which led to high specific capacitance values (up to 241 F/g), cyclic stability, and powerdensity of these materials in electrochemical measurements. These results suggest that cellulose-derivedoriginal CNF/CNT composites are sustainable and efficient carbonaceous electrodes for supercapacitors.
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| 13. |
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| 14. |
- Naboka, Olga, 1981, et al.
(author)
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Carbon Nanofibers Synthesized from Electrospun Cellulose for Advanced Materials Applications
- 2013
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In: Materials Science Forum. - 1662-9752 .- 0255-5476. ; 730-732, s. 903-908
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Conference paper (peer-reviewed)abstract
- Carbon nanofibrous sheets (conductivity 1.9 to 35.5 S×cm-1, water contact angle up to 137°) consisting of amorphous fibers with diameter of 20 - 150 nm (C:O atomic ratio 25.4 - 86.0) were synthesized by carbonization of cellulose regenerated from electrospun cellulose acetate mats with three methods of alkaline deacetylation. It was established that C:O atomic ratio, conductivity and hydrophobicity depended on the regeneration method and on the temperature of carbonization. The highest flexibility, lowest conductivity and lowest water contact angle was observed for carbon synthesized from cellulose regenerated with NaOH in ethanol (0.05 mol/l) for 24 hours at room temperature. The highest conductivity, highest water contact angle and lowest flexibility was observed for carbon synthesized from cellulose regenerated with water solution of NaOH/NaCl (3.75 M NaOH, 2.1 M NaCl) during 15 minutes at 65°C.
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| 15. |
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| 16. |
- Naboka, Olga, 1981, et al.
(author)
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Cobalt (II) Chloride Promoted Formation of Honeycomb Patterned Cellulose Acetate Films
- 2012
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In: Journal of Colloid and Interface Science. - : Elsevier BV. - 1095-7103 .- 0021-9797. ; 367:1, s. 485-493
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Journal article (peer-reviewed)abstract
- CoCl2 containing honeycomb patterned films were prepared from cellulose acetate (CA)/CoCl2/acetone solutions by the breath figure method in a wide range of humidities. Size and pore regularity depend on the CA/CoCl2 molar ratio and humidity. When replacing CoCl2 with Co(NO3)2 or CoBr2, no formation of ordered porosity in the cellulose acetate films is observed. According to data from scanning electron microscopy (SEM), Energy Dispersive X-ray Microanalysis (EDX), X-ray Diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy, the key role in the formation of honeycomb structures can be attributed to the physical and chemical properties of CoCl2 – hygroscopicity, low interaction with CA, and extraction from CA/CoCl2/acetone solution by water droplets condensed on the surface of the CA/CoCl2 solution. Obtained films are prospective for using in catalysis, hydrogen fuel cells, and optical sensing materials.
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| 17. |
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| 18. |
- Naboka, Olga, 1981, et al.
(author)
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Ni/C/SiO2 nanostructured composites synthesized by carbonization of carboxymethyl cellulose
- 2012
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In: ECCM 15 - 15th European Conference On Composite Materials, 24-28 June 2012, Venice, Italy, paper 1052 (1-7).. ; 367:1, s. 485-493
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Conference paper (peer-reviewed)abstract
- Ni/C/SiO2 porous composites were synthesized by one-pot approach by carbonization of sodium carboxymethyl cellulose/SiO2 xerogels containing NiCl2. Synthesized composites are mesoporous materials (average pore size 11.8 -15.1 nm) with the surface area 72.1 – 91.1 m2. Ni nanoparticles of 30-90 nm in diameter are evenly distributed within the volume of composites. The hydrogen sorption capacity at -196°C and 20 bar measured for as-synthesized samples was up to 0,32%.
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| 19. |
- Toomadj, Farshad, et al.
(author)
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Sensing application of nanocellulose modified with double-walled carbon nanotube and graphitized carbon nanopowder
- 2011
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In: Proceedings of the 22n Micromechanics and Microsystems Technology Europe Workshop, 19-22 June 2011, Tönsberg, Norway. ; , s. B33-
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Conference paper (peer-reviewed)abstract
- Electrically conductive nanocellulose films were prepared by immersion in well dispersed solutions of double walled carbon nanotubes or graphitized nanopow¬der. These solutions were prepared by using the surfactant cetyltrimethylammonium bromide (CTAB) under heating and stirring conditions which were followed by a short time sonication process. Electrospun cellulose and bacterial cellulose were used as a backbone of these films. Controllable modification of cellulose with conductive agents was performed by treatment with their dispersions for 24 – 72 hours. Electrical conductivities of the resulting films are from 0,009 S cm-1 to 0,395 S cm-1 which is higher or comparable to previously reported results.Some methods have been employed to study the electrical conductivity behavior of samples. The electrical conductance of the films displays a high sensitivity to strain when tensile stress is applied.
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| 20. |
- Toomadj, Farshad, et al.
(author)
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Strain Sensitivity of Carbon Nanotubes Modified Cellulose
- 2011
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In: Procedia Engineering: 25th Eurosensors Conference; Athens; Greece; 4 September 2011 through 7 September 2011. - : Elsevier BV. - 1877-7058. ; 25, s. 1353-1356
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Conference paper (peer-reviewed)abstract
- Nanostructured cellulose was modified by different concentration and volume of dispersed multi-walled carbon nanotube (MWCNT) and double-walled carbon nanotube (DWCNT) solutions and its electrical properties were studied. The resulting flexible cellulose films have an electrical conductivity sensitive to changes in CNT concentration and immersion time in solution. The conductivity increases with increasing immersion time and volume and concentration of dispersed solutions; the conductivity for bacterial cellulose (BC) pellicles modified with DWCNT was increased from 0.034 S cm-1 to 0.15 S cm-1 and for BC pellicles modified with MWCNT it was increased from 0.12 S cm-1 to 1.6 S cm-1 when the immersion time was increased from 24 h to 72 h. These results are significantly higher than in previously reported work [1].The effect of strain on the resistance during application of tensile force is shown for a simple strain gauge employing cellulose with incorporated DWCNTs. The electrical resistance of the films displays a high sensitivity to strain. It seems that this sensitivity depends on the modifying conditions, where BC pellicles which are modified in a dispersed solution with a higher concentration of CNTs show larger changes in resistance with the changes in fractional extension
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