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| 3. |
- Karlsson, Christoffer, et al.
(författare)
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Stable Deep Doping of Vapor-Phase Polymerized Poly(3,4-ethylenedioxythiophene)/Ionic Liquid Supercapacitors.
- 2016
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Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 9:16, s. 2112-2121
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Tidskriftsartikel (refereegranskat)abstract
- Liquid-solution polymerization and vapor-phase polymerization (VPP) have been used to manufacture a series of chloride- and tosylate-doped poly(3,4-ethylenedioxythiophene) (PEDOT) carbon paper electrodes. The electrochemistry, specific capacitance, and specific charge were determined for single electrodes in 1-ethyl-3-methylimidazolium dicyanamide (emim dca) ionic liquid electrolyte. VPP-PEDOT exhibits outstanding properties with a specific capacitance higher than 300 F g(-1) , the highest value reported for a PEDOT-based conducting polymer, and doping levels as high as 0.7 charges per monomer were achieved. Furthermore, symmetric PEDOT supercapacitor cells with the emim dca electrolyte exhibited a high specific capacitance (76.4 F g(-1) ) and high specific energy (19.8 Wh kg(-1) ). A Ragone plot shows that the VPP-PEDOT cells combine the high specific power of conventional ("pure") capacitors with the high specific energy of batteries, a highly sought-after target for energy storage.
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| 4. |
- Keskinen, Jari, et al.
(författare)
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Asymmetric and symmetric supercapacitors based on polypyrrole and activated carbon electrodes
- 2015
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Ingår i: Synthetic metals. - : Elsevier BV. - 0379-6779 .- 1879-3290. ; 203, s. 192-199
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Supercapacitors were prepared using either two polypyrrole (PPy) composite electrodes or one PPy composite and one activated carbon electrode. The PPy composite electrodes were either freestanding paper-like sheets or PPy films printed on graphite ink coated aluminium/PET laminate substrates, using Cladophora algae derived cellulose as the substrate or binder, respectively. The specific capacitance of the PPy electrodes was found to be about 200 F g−1 depending on the manufacturing method, yielding supercapacitors with capacitances between 0.45 and 3.8 F and energy efficiencies of over 90%. For an asymmetric device with activated carbon positive electrode and PPy negative electrode a capacitance loss of 5% was seen after 14300 cycles.
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| 5. |
- Pochard, Isabelle, et al.
(författare)
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Amine-functionalised mesoporous magnesium carbonate : Dielectric spectroscopy studies of interactions with water and stability
- 2018
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Ingår i: Materials Chemistry and Physics. - : ELSEVIER SCIENCE SA. - 0254-0584 .- 1879-3312. ; 216, s. 332-338
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Tidskriftsartikel (refereegranskat)abstract
- A mesoporous magnesium carbonate (MMC) material that was first described in 2013 is currently being investigated for several industrial and life-science-based applications. In this paper, the effect of functionalising the surface of MMC with amine groups on the water interaction properties of the material is investigated in detail. Amine functionalisation enhanced the stability and water sorption-release properties of the material. This is explained by the low affinity between amine-functionalised MMC and water molecules, as attested by the high free/total water ratio shown by dielectric spectroscopy. This low affinity had an impact on the total amount of adsorbed water at low relative humidities (RHs) but not at high RHs. The functionalisation of MMC with amine groups also stabilised the material in moist environments, hindering spontaneous crystallisation. These results provide a more fundamental understanding of the water interaction properties of MMC and are also expected to facilitate optimisation of the stability of materials like this for novel drug formulations and other life-science applications, as well as for their use in humidity control.
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| 6. |
- Tammela, Petter, et al.
(författare)
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Asymmetric supercapacitors based on carbon nanofibre and polypyrrole/nanocellulose composite electrodes
- 2015
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Ingår i: RSC Advances. - 2046-2069. ; 5:21, s. 16405-16413
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Tidskriftsartikel (refereegranskat)abstract
- Asymmetric, all-organic supercapacitors (containing an aqueous electrolyte), exhibiting a capacitance of 25 F g-1 (or 2.3 F cm-2) at a current density of 20 mA cm-2 and a maximum cell voltage of 1.6 V, are presented. The devices contain a composite consisting of polypyrrole covered Cladophora cellulose fibres (PPy-cellulose) as the positive electrode while a carbon nanofibre material, obtained by heat treatment of the same PPy-cellulose composite under nitrogen gas flow, serves as the negative electrode. Scanning and transmission electron microscopy combined with X-ray photoelectron spectroscopy data show that the heat treatment gives rise to a porous carbon nanofibre material, topologically almost identical to the original PPy-cellulose composite. The specific gravimetric capacitances of the carbon and the PPy-cellulose electrodes were found to be 59 and 146 F g-1, respectively, while the asymmetric supercapacitors exhibited a gravimetric energy density of 33 J g-1. The latter value is about two times higher than the energy densities obtainable for a symmetric PPy-cellulose device as a result of the larger cell voltage range accessible. The capacitance obtained for the asymmetric devices at a current density of 156 mA cm-2 was 11 F g-1 and cycling stability results further indicate that the capacity loss was about 23% during 1000 cycles employing a current density of 20 mA cm-2. The present results represent a significant step forward towards the realization of all-organic material based supercapacitors with aqueous electrolytes and commercially viable capacitances and energy densities.
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| 7. |
- Vall, Maria, et al.
(författare)
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Amine-Modified Mesoporous Magnesium Carbonate as an Effective Adsorbent for Azo Dyes
- 2019
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 4:2, s. 2973-2979
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Tidskriftsartikel (refereegranskat)abstract
- Mesoporous magnesium carbonate (MMC) was evaluated as a potential candidate material for removal of dyes from textile industry wastewater. The adsorption property of MMC was analyzed for three different azo dyes: reactive black 5 (RB5), amaranth (AM), and acid red 183 (AR183). Further, the effect of porosity, amine modification, ionic strength, and pH was evaluated. MMC modified with 3-(aminopropyl)triethoxysilane (aMMC) showed consistently high uptake levels for all of the azo dyes tested; the uptake of RB5, AM, and AR183 was ∼360, ∼143 and ∼170 mg/g, respectively. The results demonstrated the importance of porosity and surface chemistry in the effective adsorption of the azo dye in aqueous systems. The uptake of RB5 and AM on aMMC was not significantly affected by pH (when varied between 4 and 10), although reduced uptake of RB5 and AM was observed at pH values <2 and >12. The addition of NaCl salt at concentrations up to 1000 mM had minimal effect on the high uptake of RB5 on aMMC. The uptake of AM by aMMC was reduced by approximately 20% in the presence of NaCl even at low concentrations. The uptake of AR183 by aMMC varied noticeably by changes in pH and no specific trend was observed. The presence of NaCl also adversely affected the uptake of AR183 on aMMC. The adsorption of the azo dye on aMMC was most likely driven by electrostatic interactions. We show here that aMMC is a potential candidate adsorbent for the effective removal of azo dyes from textile wastewaters.
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| 9. |
- Vall, Maria, et al.
(författare)
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Carbon dioxide adsorption on mesoporous magnesium carbonate
- 2019
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Ingår i: Energy Procedia. - : Elsevier. - 1876-6102. ; 158, s. 4671-4676
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Tidskriftsartikel (refereegranskat)abstract
- Mesoporous magnesium carbonate (MMC) was synthesized and tested for its ability to separate CO2 from N2. The pure gas CO2 uptake of MMC was around 1.5 mmol/g at 101 kPa, 0 °C. The N2 uptake under the same conditions was less than 0.1 mmol/g. Al(NO3)3, Al2O3, K2CO3 and KNO3 were introduced into the porous structure of MMC as additives. All of the additives tested increased the CO2 uptake of MMC and increased its selectivity towards CO2. The incorporation of 5 wt.% K2CO3 increased the CO2 uptake of MMC up to over 3.2 mmol/g. The ideally adsorbed solution theory was used to calculate the CO2 selectivity of MMC and MMC with additives for a hypothetical gas mixture that contained 15% CO2: 85% N2. The CO2 selectivity at 101 kPa (0 °C) was around 60. MMC with 5 wt.% K2CO3 had a CO2 selectivity of over 150 under the same conditions. Vacuum swing cyclic CO2 adsorption/desorption showed that the CO2 uptake on MMC with 5 wt.% K2CO3 decreased after each cycle. Heat regeneration (up to 250 °C, for 10 minutes) could recover most of the lost CO2 capacity after each cycle. Heat regeneration indicatively improved the cyclic performance of this adsorbent. MMC with 5 wt.% K2CO3 was the best performing adsorbent in this study and can potentially be further developed into a good CO2 adsorbent for temperature swing adsorption (TSA) processes.
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| 10. |
- Vall, Maria, et al.
(författare)
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Effects of amine modification of mesoporous magnesium carbonate on controlled drug release
- 2017
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Ingår i: International Journal of Pharmaceutics. - : Elsevier BV. - 0378-5173 .- 1873-3476. ; 524, s. 141-147
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Tidskriftsartikel (refereegranskat)abstract
- (3-Aminopropyl)triethoxysilane (APTES) was used to modify the surface of mesoporous magnesium carbonate (MMC). The as-synthesized MMC had an average pore diameter of ∼5 nm, but amine grafting occurred preferentially on the walls of the largest MMC pores. Analysis of ibuprofen (IBU) loading and release showed that IBU remained stable in the amorphous phase in all the MMC and modified MMC samples. The kinetics of IBU release from the modified MMC were assessed and used to evaluate the effects of the different functional groups. The release rate showed that the release of IBU could be controlled by adjusting the amine surface coverage of MMC and also by changing the surface groups. It was concluded that the interaction between the grafted, functional groups in the modified MMC and the OH in the carboxyl groups of IBU was the most important factor for prolonging the release of the drug. These results are expected to lead to investigation of other as yet unexplored applications for MMC, including using it as a plastic additive and for gas separation.
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