| 1. |
- Abrahamsson, Tobias, et al.
(författare)
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Investigating the role of polymer size on ionic conductivity in free-standing hyperbranched polyelectrolyte membranes
- 2021
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Ingår i: Polymer. - : Elsevier. - 0032-3861 .- 1873-2291. ; 223
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Tidskriftsartikel (refereegranskat)abstract
- Polymer-based ion exchange membranes (IEMs) are utilized for many applications such as in water desalination, energy storage, fuel cells and in electrophoretic drug delivery devices, exemplified by the organic electronic ion pump (OEIP). The bulk of current research is primarily focused on finding highly conductive and stable IEM materials. Even though great progress has been made, a lack of fundamental understanding of how specific polymer properties affect ionic transport capabilities still remains. This leads to uncertainty in how to proceed with synthetic approaches for designing better IEM materials. In this study, an investigation of the structure-property relationship between polymer size and ionic conductivity was performed by comparing a series of membranes, based on ionically charged hyperbranched polyglycerol of different polymer sizes. Observing an increase in ionic conductivity associated with increasing polymer size and greater electrolyte exclusion, indi-cating an ionic transportation phenomenon not exclusively based on membrane electrolyte uptake. These findings further our understanding of ion transport phenomena in semi-permeable membranes and indicate a strong starting point for future design and synthesis of IEM polymers to achieve broader capabilities for a variety of ion transport-based applications.
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| 2. |
- Abrahamsson, Tobias, 1991-
(författare)
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Synthetic Functionalities for Ion and Electron Conductive Polymers : Applications in Organic Electronics and Biological Interfaces
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the search for understanding and communicating with all biological systems, in humans, animals, plants, and even microorganisms, we find a common language of all communicating via electrons, ions and molecules. Since the discovery of organic electronics, the ability to bridge the gap and communicate be-tween modern technology and biology has emerged. Organic chemistry pro-vides us with tools for understanding and a material platform of polymer electronics for communication. Such insights give us not only the ability to observe fundamental phenomenon but to actively design and construct materials with chemical functionalities towards better interfaces and applications. Organic electronic materials and devices have found their way to be implemented in the field of medicine for diagnostic and therapeutic purposes, but also in water purification and to help tackle the monumental task in creating the next generation of sustainable energy production and storage. Ultimately it’s safe to say that organic electronics are not going to replace our traditional technology based on inorganic materials but rather the two fields can find a way to complement each other for various purposes and applications. Compared to conventional silicon based technology, production of carbon-based organic electronic polymer materials are extremely cheap and devices can even be made flexible and soft with great compatibility towards biology. The main focus of this thesis has been developing and synthesizing new types of organic electronic and ionic conductive polymeric materials. Rational chemical design and modifications of the materials have been utilized to introduce specific functionalities to the materials. The functionalities serving the purpose to facilitate ion and electron conductive charge transport for organic electronics and with biological interface implementation of the polymer materials. Multi-functional ionic conductive hyperbranched polyglycerol polyelectrolytes (dendrolytes) were developed comprising both ionically charged groups and cross-linkable groups. The hyperbranched polyglycerol core structure of the material possesses a hydrophilic solvating platform for both ions and maintenance of solvent molecules, while being a biocompatible structure. Coupled with the peripheral charged ionic functionalities of the polymer, the dendrolyte materials are highly ionic conductive and selective towards cationic and anionic charged atoms and large molecules when implemented as ion-exchange membranes. Homogenous ion-exchange membrane casting has been achieved by the implementation of cross-linkable functionalities in the dendrolytes, utilizing robust click-chemistry for efficient micro and macro fabrication processing of the ion-ex-change membranes for organic electronic devices. The ion-exchange membrane material was implemented in electrophoretic drug delivery devices (organic electronic ion pumps), which are used for delivery of ions and neurotransmitters with spatiotemporal resolution and are able to communicate and be used for therapeutic drug delivery purposes in biological interfaces. The dendrolyte materials were also able to form free-standing membranes, making it possible for implementation in fuel cell and desalination purposes. Trimeric conjugated thiophene pre-polymer structures were also developed in the thesis and synthesized for the purpose of implementation of the material in vivo to form electrically conductive polymer structures, and in such manner to be able to create electrodes and ultimately to connect with the central nervous system. The conjugated pre-polymers being both water soluble and enzymatically polymerizable serve as a platform to realize such a concept. Also, modifying the trimeric structure with cross-linkable functionality created the capability to form better interfaces and stability towards biological environments.
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| 3. |
- Ahmed, Fareed, et al.
(författare)
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Manufacturing Poly(3,4-Ethylenedioxythiophene) Electrocatalytic Sheets for Large-Scale H2O2 Production
- 2022
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Ingår i: Advanced Sustainable Systems. - : John Wiley and Sons Inc. - 2366-7486. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- Producing thick films of conducting polymers by a low-cost manufacturing technique would enable new applications. However, removing huge solvent volume from diluted suspension or dispersion (1–3 wt%) in which conducting polymers are typically obtained is a true manufacturing challenge. In this work, a procedure is proposed to quickly remove water from the conducting polymer poly(3,4-ethylenedioxythiophene:poly(4-styrene sulfonate) (PEDOT:PSS) suspension. The PEDOT:PSS suspension is first flocculated with 1 m H2SO4 transforming PEDOT nanoparticles (≈50–500 nm) into soft microparticles. A filtration process inspired by pulp dewatering in a paper machine on a wire mesh with apertures dimension between 60 µm and 0.5 mm leads to thick free-standing films (≈0.5 mm). Wire mesh clogging that hinders dewatering (known as dead-end filtration) is overcome by adding to the flocculated PEDOT:PSS dispersion carbon fibers that aggregate and form efficient water channels. Moreover, this enables fast formation of thick layers under simple atmospheric pressure filtration, thus making the process truly scalable. Thick freestanding PEDOT films thus obtained are used as electrocatalysts for efficient reduction of oxygen to hydrogen peroxide, a promising green chemical and fuel. The inhomogeneity of the films does not affect their electrochemical function. © 2021 The Authors.
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| 4. |
- Ajjan, Fátima, 1986-, et al.
(författare)
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Doped Conjugated Polymer Enclosing a Redox Polymer : Wiring Polyquinones with Poly(3,4‐Ethylenedioxythiophene)
- 2020
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Ingår i: Advanced Energy and Sustainability Research. - : John Wiley & Sons. - 2699-9412. ; 1:2
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Tidskriftsartikel (refereegranskat)abstract
- The mass implementation of renewable energies is limited by the absence of efficient and affordable technology to store electrical energy. Thus, the development of new materials is needed to improve the performance of actual devices such as batteries or supercapacitors. Herein, the facile consecutive chemically oxidative polymerization of poly(1-amino-5-chloroanthraquinone) (PACA) and poly(3,4-ethylenedioxythiophene (PEDOT) resulting in a water dispersible material PACA-PEDOT is shown. The water-based slurry made of PACA-PEDOT nanoparticles can be processed as film coated in ambient atmosphere, a critical feature for scaling up the electrode manufacturing. The novel redox polymer electrode is a nanocomposite that withstands rapid charging (16 A g−1) and delivers high power (5000 W kg−1). At lower current density its storage capacity is high (198 mAh g−1) and displays improved cycling stability (60% after 5000 cycles). Its great electrochemical performance results from the combination of the redox reversibility of the quinone groups in PACA that allows a high amount of charge storage via Faradaic reactions and the high electronic conductivity of PEDOT to access to the redox-active sites. These promising results demonstrate the potential of PACA-PEDOT to make easily organic electrodes from a water-coating process, without toxic metals, and operating in non-flammable aqueous electrolyte for large scale pseudocapacitors.
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| 5. |
- Bamgbopa, Musbaudeen O., et al.
(författare)
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Towards eco-friendly redox flow batteries with all bio-sourced cell components
- 2022
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Ingår i: Journal of Energy Storage. - : ELSEVIER. - 2352-152X .- 2352-1538. ; 50
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Forskningsöversikt (refereegranskat)abstract
- Recent research and few pilot deployments have demonstrated promising aqueous organic redox flow battery (RFB) systems. However, the claim that these organic RFB systems are eco-friendlier energy storage than Lithium-ion batteries and aqueous inorganic metallic RFB counterparts needs reinforcement, primarily if cell components other than redox-active species are still based on unsustainable materials. This thesis of the present work presents the prospects of achieving future eco-friendly RFBs with higher consideration for sustainability by adopting significant amounts of abundant bio-sourced/based materials for all main cell components. As we highlight the promising sources of the energy materials from a review of previous studies, we infer that plant derived quinones and other organic polymers may continue to dominate the organic redox-active species space. Furthermore, a candidate methodology to accomplish porous electrodes and membranes/separators of the eco-friendly RFBs is to apply stand-alone bio-based/sourced fibrils derived from cellulose, lignin, chitin, among other materials. These materials can be combined with (un)carbonised biomass or food wastes & residues to impart conductivity, catalytic activity, and ion selectivity. We explore symmetric chemistry as an ideal system for the eco-friendly RFBs of the discourse, given interplay between the electrolyte, electrode material and membrane dictates energy efficiency and cycling stability. These strategies also need to be coupled with further improvements to achieve reliability.
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| 6. |
- Ding, Penghui, 1994-
(författare)
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Organic Materials-based Electrochemical Flow Cells for Energy Applications
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- To meet the 2015 Paris Agreement requirement of limiting global warming to 1.5 °C, the transition from fossil fuels to renewables (solar and wind) necessitates a rapid change of the energy landscape. The decline of the price for electricity from solar panels and wind turbines is so fast over the last decade that green electricity competes economically with electricity generated from coal, oil, and gas. Considering the output from renewable energy sources is electric current, the conversion and storage of green electricity is the key to the paradigm shift. Both conversion and storage imply transformation of electrical energy into chemical energy of molecules. The former means production of multipurpose energetic molecules. Here such a molecule is hydrogen peroxide, a green oxidant, and our aim is to advance its electrochemical production. The latter is concerned with making the chemical energy readily transformable back into electricity in batteries. In electrochemistry, H-cells are usually used in screening materials and mechanistic understanding of relevant processes. However, the results of H-cell studies sometimes do not directly translate to upscaled systems, such as flow cells. Electrochemical flow cells are attracting attention due to the ability to decouple capacity and power, the long operation time, and the decreased diffusion layer thickness and ohmic resistance. Most flow cells today use inorganic materials, and they are expensive and based on unsustainable mining processes in some geographically concentrated regions. Organic materials, on the contrary, are cheap and readily designed via molecular engineering and electro-organic synthesis. In this thesis, organic materials-based flow cells will be constructed for energy conversion and storage studies. We start with making free-standing poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films with a thickness >50 μm by vacuum filtration, which then are used in electrochemical production of hydrogen peroxide (H2O2) in a H-cell. Due to some drawbacks listed above, we shifted our focus to flow cells. The cathodic generation of H2O2 is combined with oxygen evolution reaction (OER) using nickel (II) oxide (NiO) to explore the possibility of using a polymer material in a flow cell environment. This flow cell system could reach a faradaic efficiency of 80% and the system loss is analyzed from different angles. However, the OER is kinetically sluggish and would need precious catalysts to drive the reaction. Instead of turning to precious catalysts, we proposed to replace the OER in the device with the oxidation of a water-soluble organic molecule oxidation, 4,5-dihydroxy-1,3-benzenedisulfonic acid disodium salt monohydrate (tiron/BQDS). The tiron oxidation is fast and does not need a catalyst. The tiron transport phenomena are investigated and we find that migration—a less recognized player—has a big role in regulating tiron transport. The last part of the thesis introduces a biomass-based membrane made from cellulose for a tiron-based aqueous organic redox flow battery. The environmentally friendly nanocellulose membranes display reduced crossover of quinone redox couples, higher discharge capacity, and better reusability than the commercial fluoropolymer Nafion™ 115 membranes. We hope the present thesis, which deals with various aspects of flow cells from organic material design to system transport phenomena, will stimulate more people to work on this fascinating topic, paving the way for electrification of everything by tunable and sustainable organic molecules.
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| 7. |
- Ghorbani Shiraz, Hamid, 1989-, et al.
(författare)
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3R-TaS2 as an Intercalation-Dependent Electrified Interface for Hydrogen Reduction and Oxidation Reactions
- 2022
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 126:40, s. 17056-17065
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogen technology, as a future breakthrough for the energy industry, has been defined as an environmentally friendly, renewable, and high-power energy carrier. The green production of hydrogen, which mainly relies on electrocatalysts, is limited by the high cost and/ or the performance of the catalytic system. Recently, studies have been conducted in search of bifunctional electrocatalysts accelerating both the hydrogen evolution reaction (HER) and the hydrogen oxidation reaction (HOR). Herein, we report the investigation of the high efficiency bifunctional electrocatalyst TaS2 for both the HER and the HOR along with the asymmetric effect of inhibition by organic intercalation. The linear organic agent, to boost the electron donor property and to ease the process of intercalation, provides a higher interlayer gap in the tandem structure of utilized nanosheets. XRD and XPS data reveal an increase in the interlayer distance of 22%. The HER and the HOR were characterized in a Pt group metal-free electrochemical system. The pristine sample shows a low overpotential of -0.016 Vat the onset. The intercalated sample demonstrates a large shift in its performance for the HER. It is revealed that the intercalation is a potential key strategy for tuning the performance of this family of catalysts. The inhibition of the HER by intercalation is considered as the increase in the operational window of a water-based electrolyte on a negative electrode, which is relevant to technologies of electrochemical energy storage.
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| 8. |
- Ghorbani Shiraz, Hamid, et al.
(författare)
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Effect of Oxygen Poisoning on the Bidirectional Hydrogen Electrocatalysis in TaS2 Nanosheets
- 2023
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Ingår i: The Journal of Physical Chemistry C. - : AMER CHEMICAL SOC. - 1932-7447 .- 1932-7455. ; 127:12, s. 5825-5832
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Tidskriftsartikel (refereegranskat)abstract
- Sustainable production of hydrogen gas, a green energy carrier of high density, is possible only by electrolysis of water based on the hydrogen evolution reaction (HER). Here, we report the effect of oxygen poisoning on the efficiency of hydrogen production and the consumption by the HER and the hydrogen oxidation reaction (HOR), respectively, on the interface of platinum group metal-free electrocatalyst TaS2 in pristine form and intercalated by the organic Lewis base hexylamine. The state of the surface probed by photoelectron spectroscopy was significantly altered by both Lewis base doping and oxygen poisoning. This alteration dramatically affects the hydrogen production efficiency in the HER, while the back process by the HOR was less sensitive to the changes in the surface states of the electrocatalysts. The oxygenated and intercalated electrocatalyst shows more than 2 x 105 times lower exchange current density of the HER compared to pristine oxygenated materials.
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| 9. |
- Ghorbani Shiraz, Hamid, et al.
(författare)
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Towards electrochemical hydrogen storage in liquid organic hydrogen carriers via proton-coupled electron transfers
- 2022
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Ingår i: Journal of Energy Challenges and Mechanics. - : Elsevier. - 2056-9386. ; 73, s. 292-300
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Tidskriftsartikel (refereegranskat)abstract
- Green hydrogen is identified as one of the prime clean energy carriers due to its high energy density and a zero emission of CO2. A possible solution for the transport of H2 in a safe and low-cost way is in the form of liquid organic hydrogen carriers (LOHCs). As an alternative to loading LOHC with H2 via a two-step procedure involving preliminary electrolytic production of H2 and subsequent chemical hydrogenation of the LOHC, we explore here the possibility of electrochemical hydrogen storage (EHS) via conversion of proton of a proton donor into a hydrogen atom involved in covalent bonds with the LOHC (R) via a protoncoupled electron transfer (PCET) reaction: . We chose 9-fluorenone/ fluorenol (Fnone/Fnol) conversion as such a model PCET reaction. The electrochemical activation of Fnone via two sequential electron transfers was monitored with in-situ and operando spectroscopies in absence and in presence of different alcohols as proton donors of different reactivity, which enabled us to both quantify and get the mechanistic insight on PCET. The possibility of hydrogen extraction from the loaded carrier molecule was illustrated by chemical activation.
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| 10. |
- Gueskine, Viktor, et al.
(författare)
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Molecular Oxygen Activation at a Conducting Polymer: Electrochemical Oxygen Reduction Reaction at PEDOT Revisited, a Theoretical Study
- 2020
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Ingår i: The Journal of Physical Chemistry C. - : AMER CHEMICAL SOC. - 1932-7447 .- 1932-7455. ; 124:24, s. 13263-13272
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Tidskriftsartikel (refereegranskat)abstract
- Molecular oxygen requires activation in order to be reduced, which prompts extensive searching for efficient and sustainable electrode materials to drive electrochemical oxygen reduction reaction (ORR), of primary importance for energy production and storage. A conjugated polymer PEDOT is a metal-free material for which promising ORR experimental results have been obtained. However, sound theoretical understanding of this reaction at an organic electrode is insufficient, as the concepts inherited from electrocatalysis at transition metals are not necessarily relevant for a molecular organic material. In this work, we critically analyze the basics of electrochemical ORR and build a model for our DFT calculations of the reaction thermodynamics based on this analysis. Altogether, this work leads to a conclusion that outer sphere electron transfer that currently attracts increasing attention in the context of ORR is a viable mechanism at a conducting polymer electrode.
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