| 1. |
- Adolfsson, Karin H., et al.
(författare)
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Importance of Surface Functionalities for Antibacterial Properties of Carbon Spheres
- 2019
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Ingår i: Advanced Sustainable Systems. - : Wiley. - 2366-7486.
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Tidskriftsartikel (refereegranskat)abstract
- Carbon spheres (CS) are interesting materials for antibacterial applications. Herein, CS are produced by a green process utilizing microwave-assisted hydrothermal treatment of cellulose. The CS are then postmodified in acidic and basic solutions to evaluate the influence of different functionalities on antibacterial properties. CS contain OH/COOH, C Symbol of the Klingon Empire C, and C Symbol of the Klingon Empire O functionalities, while O-CS produced by acid treatment of CS have additional COOH, and NH/NH2 groups, resulting in carbon spheres with negatively and positively charged groups in dispersion. Treatment with base (Na-CS) removes low molecular weight species with oxygen and results in carbon spheres with the highest C/O ratio. CS, O-CS, and Na-CS have nonporous morphology and are in micro/nanometer sizes, although, smaller sized spheres, hollow spheres, and fragments are also attained in the case of O-CS. O-CS show antibacterial activity toward both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Pseudomonas aeruginosa (P. aeruginosa). The minimum inhibitory concentration is 200 and 400 mu g mL(-1) for S. aureus and P. aeruginosa, respectively, and is achieved only after 3 h of incubation. Neither CS nor Na-CS exhibit antibacterial activity. The antibacterial activity is suggested to originate from electrostatic interactions between O-CS and the bacteria.
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| 2. |
- Che, Canyan, 1988-, et al.
(författare)
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Twinning Lignosulfonate with a Conducting Polymer via Counter-Ion Exchange for Large-Scale Electrical Storage
- 2019
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Ingår i: Advanced Sustainable Systems. - : Wiley-VCH Verlag. - 2366-7486. ; 3:9
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Tidskriftsartikel (refereegranskat)abstract
- Lignosulfonate (LS) is a large-scale surplus product of the forest and paper industries, and has primarily been utilized as a low-cost plasticizer in making concrete for the construction industry. LS is an anionic redox-active polyelectrolyte and is a promising candidate to boost the charge capacity of the positive electrode (positrode) in redox-supercapacitors. Here, the physical-chemical investigation of how this biopolymer incorporates into the conducting polymer PEDOT matrix, of the positrode, by means of counter-ion exchange is reported. Upon successful incorporation, an optimal access to redox moieties is achieved, which provides a 63% increase of the resulting stored electrical charge by reversible redox interconversion. The effects of pH, ionic strength, and concentrations, of included components, on the polymer–polymer interactions are optimized to exploit the biopolymer-associated redox currents. Further, the explored LS-conducting polymer incorporation strategy, via aqueous synthesis, is evaluated in an up-scaling effort toward large-scale electrical energy storage technology. By using an up-scaled production protocol, integration of the biopolymer within the conducting polymer matrix by counter-ion exchange is confirmed and the PEDOT-LS synthesized through optimized strategy reaches an improved charge capacity of 44.6 mAh g−1.
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| 3. |
- Edberg, Jesper, et al.
(författare)
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Improving the Performance of Paper Supercapacitors Using Redox Molecules from Plants
- 2019
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Ingår i: ADVANCED SUSTAINABLE SYSTEMS. - : WILEY-V C H VERLAG GMBH. - 2366-7486. ; 3:8
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Tidskriftsartikel (refereegranskat)abstract
- A supercapacitor made from organic and nature-based materials, such as conductive polymers (PEDOT:PSS), nanocellulose, and an the organic dye molecule (alizarin), is demonstrated. The dye molecule, which historically was extracted from the roots of the plant rubia tinctorum, is here responsible for the improvement in energy storage capacity, while the conductive polymer provides bulk charge transport within the composite electrode. The forest-based nanocellulose component provides a mechanically strong and nonporous network onto which the conductive polymer self-organizes. The electrical and electrochemical properties of the material composition are investigated and prototype redox-enhanced supercapacitor devices with excellent specific capacitance exceeding 400 F g(-1) and an operational stability over >1000 cycles are demonstrated. This new class of supercapacitors, which in part are based on organic materials from plants, represents an important step toward a green and sustainable energy technology.
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| 4. |
- Gryszel, Maciej, et al.
(författare)
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Water-Soluble Organic Dyes as Molecular Photocatalysts for H2O2 Evolution
- 2019
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Ingår i: Advanced Sustainable Systems. - : Wiley-VCH Verlagsgesellschaft. - 2366-7486 .- 2366-7486. ; 3:8, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- Photochemical generation of hydrogen peroxide via oxygen reduction is a critical component of emerging sustainable energy conversion concepts. Light‐absorbing semiconductors as well as electrodes modified with sensitizers typically catalyze oxygen photoreduction to hydrogen peroxide. Here, it is reported that, in contrast to these heterogeneous systems, a homogeneous solution of a metal‐free organic dye can perform the whole catalytic cycle of hydrogen peroxide photoevolution itself. This cycle can proceed with simultaneous oxidation of various organic molecules as electron donors, or even water. In the three water‐soluble dyes that are experimented with, photoevolution of peroxide occurs favorably at neutral to basic pH. The reaction is first order with respect to dye concentration, and evidence implicates a single‐electron reduction pathway with superoxide as an intermediate. Photostability of the dyes over time correlates with increased oxidation potential of the molecule. The finding that hydrogen peroxide can be produced in aqueous solution with single fully organic molecules performing the entire photocatalytic cycle creates a new avenue for the peroxide carbon free energy cycle.
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| 5. |
- Mitraka, Evangelia, 1986-, et al.
(författare)
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Electrocatalytic Production of Hydrogen Peroxide with Poly(3,4-ethylenedioxythiophene) Electrodes
- 2019
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Ingår i: Advanced Sustainable Systems. - : Wiley-VCH Verlagsgesellschaft. - 2366-7486 .- 2366-7486. ; 3:2, s. 1-6
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Tidskriftsartikel (refereegranskat)abstract
- Electrocatalysis for energy‐efficient chemical transformations is a central concept behind sustainable technologies. Numerous efforts focus on synthesizing hydrogen peroxide, a major industrial chemical and potential fuel, using simple and green methods. Electrochemical synthesis of peroxide is a promising route. Herein it is demonstrated that the conducting polymer poly(3,4‐ethylenedioxythiophene), PEDOT, is an efficient and selective heterogeneous catalyst for the direct reduction of oxygen to hydrogen peroxide. While many metallic catalysts are known to generate peroxide, they subsequently catalyze decomposition of peroxide to water. PEDOT electrodes can support continuous generation of high concentrations of peroxide with Faraday efficiency remaining close to 100%. The mechanisms of PEDOT‐catalyzed reduction of O2 to H2O2 using in situ spectroscopic techniques and theoretical calculations, which both corroborate the existence of a chemisorbed reactive intermediate on the polymer chains that kinetically favors the selective reduction reaction to H2O2, are explored. These results offer a viable method for peroxide electrosynthesis and open new possibilities for intrinsic catalytic properties of conducting polymers.
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| 6. |
- Mitraka, Evangelia, et al.
(författare)
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PEDOT-Cellulose Gas Diffusion Electrodes for Disposable Fuel Cells
- 2019
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Ingår i: Advanced Sustainable Systems. - : Wiley-VCH Verlag. - 2366-7486. ; 3:12
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Tidskriftsartikel (refereegranskat)abstract
- The mass implementation of renewable energy sources is limited by the lack of energy storage solutions operating on various timescales. Electrochemical technologies such as supercapacitors and batteries cannot handle long storage time because of self-discharge issues. The combination of fuel storage technology and fuel cells is an attractive solution for long storage times. In that context, large-scale fuel cell solutions are required for massive energy storage in cities, which leads to possible concepts such as low-cost disposable fully organic membrane assemblies in fuel cells to avoid regeneration of expensive poisoned electrodes. Here, the formation of an organic gas diffusion electrode (GDE) fabricated by paper-making production, combined with in situ polymerization is demonstrated for the first time. Cellulose is used as a 3D scaffold functionalized with poly(3,4-ethylenedioxythiophene) (PEDOT) serving as both an electrical conductor and an electrocatalyst of high efficiency for the oxygen reduction reaction. The PEDOT-cellulose porous GDE is implemented in a membrane assembly and demonstrated in a H2-O2 fuel cell. The demonstration of low-cost material/manufacturing that is environmentally friendly is a paradigm shift in the development of fuel cells for a sustainable society.
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