| 1. |
- 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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| 2. |
- Kuzmenko, Volodymyr, 1987, et al.
(författare)
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Sustainable carbon nanofibers/nanotubes composites from cellulose as electrodes for supercapacitors
- 2015
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 90:2, s. 1490-1496
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Tidskriftsartikel (refereegranskat)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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