| 1. |
- Ahmed, Mukhtiar
(författare)
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Fluorine-Free Ionic Liquid Based Electrolytes: Synthesis and Structural Characterization
- 2022
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Since their introduction by Sony in 1990, lithium-ion batteries (LIBs) have acquired a sizable market share. They have the best energy densities, a high open circuit voltage, a low self-discharge rate, no memory effect, and a slow loss of charge when not in use. These properties make them the most popular rechargeable batteries for portable gadgets, electric vehicles and aerospace applications. They do, however, pose major safety issues since the electrolytes are made up of fluorinated salts dissolved in volatile organic solvents, the former being meta-stable at ambient temperature and the latter being flammable a with high vapour pressure. Thus, there is an urge to develop thermally and electrochemically stable non-fluorinated electrolytes to improve the safety and performance of batteries. Electrolytes based on ionic liquids (ILs) in general offer a range of suitable advantages including low volatility and high thermal and electrochemical stabilities,and can additionally be made fluorine-free. In general, their physicochemical properties are determined by the interactions between the cations and anions, which are controlled by the chemical functionalities present, with vast freedom in structural design to reduce these interactions and enhance also the ion mobilities. In this study, favoring from of “structural design” three different families of fluorine-free ionic liquids-based electrolytes are designed and created. These families of ILs comprising n- tetrabutylphosphonium, imidazolium, pyridinium based cations and pyridine, pyrazine and ether functionalized salicylate-based anions. The structures and purity of these new ILs are characterized by using multinuclear NMR, FTIR and mass spectrometry. Several features and properties of the novel electrolytes are investigated; thermogravimetric analysis, differential scanning calorimetry, ionic conductivity and electrochemical stability. These studies are further complemented by using PFG NMR diffusometry to understand the possible interaction mechanisms between the oppositely charged ions within the electrolytes, and especially, the influence of Li+ addition in the IL-based electrolytes.
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| 2. |
- Ai, Chenxiang, et al.
(författare)
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A knitting copolymerization Strategy to Build Porous Polytriazolium Salts for Removal of Anionic Dyes and MnO4−
- 2022
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Ingår i: Macromolecular rapid communications. - : Wiley. - 1022-1336 .- 1521-3927. ; 43:15
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Tidskriftsartikel (refereegranskat)abstract
- Although considerable efforts have been devoted to novel ionic porous networks (IPNs), the development of them in a scalable manner to tackle the issues in pollutant treatment by adsorption remains an imminent challenge. Herein, inspired by natural spider webs, a knitting copolymerization strategy is proposed to construct analogue triazolium salt-based porous networks (IPN-CSUs). It is not only convenient to incorporate the cationic motifs into the network, but easy to control over the contents of ionic pairs. The as-prepared IPN-CSUs displays a high surface area of 924 m2 g−1, a large pore volume of 1.27 cm3 g−1 and abundant ionic sites, thereby exhibiting fast adsorption rate and high adsorption capacity towards organic and inorganic pollutants. The kinetics and thermodynamics study reveal that the adsorption followed a pseudo-second-order kinetic model and Langmuir isotherm model correspondingly. Specifically, the maximum adsorption capacity of the IPN-CSUs is as high as 1.82 mg mg−1 for permanganate ions and up to 0.54 mg mg−1 for methyl orange, which stands out among the previously reported porous adsorbents so far. It is expected that the strategy reported herein can be extended to the development of other potential efficient adsorbents in water purifications.
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| 3. |
- Ai, Chenxiang, et al.
(författare)
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One-pot construction of nitrogen-rich polymeric ionic porous networks for effective CO2 capture and fixation
- 2022
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Ingår i: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 13:1, s. 121-129
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Tidskriftsartikel (refereegranskat)abstract
- Facile preparation of ionic porous networks (IPNs) with large and permanent porosity is highly desirable for CO2 capture and transformation but remains a challenge. Here we report a one-pot base-mediated construction of nitrogen-rich IPNs through a combination of nucleophilic substitution and quaternisation chemistry from H-imidazole. This strategy, as proven by the model reactions of 1H-imidazole or 1-methyl-1H-imidazole with cyanuric chloride, allows for fine regulation of porosity and physicochemical properties, leading to nitrogen-rich IPNs featuring abundant ionic units and radicals. The as-prepared networks, termed IPN-CSUs, efficiently capture CO2 (80.1 cc g−1 at 273 K/1 bar) with an ideal CO2/N2 selectivity of 139.7. They can also effectively catalyse the cycloaddition reaction between CO2 and epoxides with high yields of up to 99% under mild conditions (0.1 MPa, 298 K), suggesting their possible applications in the fields of both selective molecular separation and conversion. Unlike the previously known strategies generally involving single coupling chemistry, our strategy combining two coupling routes in one pot appears to be unique and potentially applicable to other building blocks.
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| 4. |
- Álvarez-Gómez, Ainhoa, et al.
(författare)
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Polyacrylonitrile-b-Polystyrene Block Copolymer-Derived Hierarchical Porous Carbon Materials for Supercapacitor
- 2022
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Ingår i: Polymers. - : MDPI AG. - 2073-4360. ; 14:23
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Tidskriftsartikel (refereegranskat)abstract
- The use of block copolymers as a sacrificial template has been demonstrated to be a powerful method for obtaining porous carbons as electrode materials in energy storage devices. In this work, a block copolymer of polystyrene and polyacrylonitrile (PS−b−PAN) has been used as a precursor to produce fibers by electrospinning and powdered carbons, showing high carbon yield (~50%) due to a low sacrificial block content (fPS ≈ 0.16). Both materials have been compared structurally (in addition to comparing their electrochemical behavior). The porous carbon fibers showed superior pore formation capability and exhibited a hierarchical porous structure, with small and large mesopores and a relatively high surface area (~492 m2/g) with a considerable quantity of O/N surface content, which translates into outstanding electrochemical performance with excellent cycle stability (close to 100% capacitance retention after 10,000 cycles) and high capacitance value (254 F/g measured at 1 A/g).
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| 5. |
- Héraly, Frédéric, et al.
(författare)
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Nanodancing with Moisture : Humidity-Sensitive Bilayer Actuator Derived from Cellulose Nanofibrils and Reduced Graphene Oxide
- 2022
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Ingår i: Advanced Intelligent Systems. - : Wiley. - 2640-4567. ; 4:1
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Tidskriftsartikel (refereegranskat)abstract
- Bilayer actuators, traditionally consisting of two laminated materials, are the most common types of soft or hybrid actuators. Herein, a nanomaterial-based organic–inorganic humidity-sensitive bilayer actuator composed of TEMPO-oxidized cellulose nanofibrils (TCNF-Na+) and reduced graphene oxide (rGO) sheets is presented. The hybrid actuator displays a large humidity-driven locomotion with an atypical fast unbending. Cationic exchange of the anionically charged TCNF-Na+ and control of the layer thickness is used to tune and dictate the locomotion and actuator's response to humidity variations. Assembly of a self-oscillating electrical circuit, that includes a conductive rGO layer, displays autonomous on-and-off lighting in response to actuation-driven alternating electrical heating.
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| 6. |
- Liu, Jinrong, et al.
(författare)
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Fully Biobased Photothermal Films and Coatings for Indoor Ultraviolet Radiation and Heat Management
- 2022
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 14:10, s. 12693-12702
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Tidskriftsartikel (refereegranskat)abstract
- Sustainable materials are needed to mitigate against the increase in energy consumption resulting from population growth and urbanization. Here, we report fully biobased nanocomposite films and coatings that display efficient photothermal activity and selective absorption of ultraviolet (UV) radiation. The nanocomposites with 20 wt % of lignin nanoparticles (LNPs) embedded in a chitosan matrix displayed an efficient UV blocking of 97% at 400 nm along with solar energy-harvesting properties. The reflectance spectra of the nanocomposite films revealed the importance of well-dispersed nanoparticles in the matrix to achieve efficient UV-blocking properties. Finally, yet importantly, we demonstrate the nanocomposites with 20 wt % LNPs as photothermal glass coatings for passive cooling of indoor temperature by simply tailoring the coating thickness. Under simulated solar irradiation of 100 mW/cm2, the 20 μm coating achieved a 58% decrease in the temperature increment in comparison to the system with uncoated glass. These renewable nanocomposite films and coatings are highly promising sustainable solutions to facilitate indoor thermal management and improve human health and well-being.
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| 7. |
- Liu, Si-hua, et al.
(författare)
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Smart Hydrogen Atoms in Heterocyclic Cations of 1,2,4-Triazolium-Type Poly(ionic liquid)s
- 2022
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Ingår i: Accounts of Chemical Research. - : American Chemical Society (ACS). - 0001-4842 .- 1520-4898. ; 55:24, s. 3675-3687
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Forskningsöversikt (refereegranskat)abstract
- Discovering and constructing molecular functionality platforms for materials chemistry innovation has been a persistent target in the fields of chemistry, materials, and engineering. Around this task, basic scientific questions can be asked, novel functional materials can be synthesized, and efficient system functionality can be established. Poly(ionic liquid)s (PILs) have attracted growing interest far beyond polymer science and are now considered an interdisciplinary crossing point between multiple research areas due to their designable chemical structure, intriguing physicochemical properties, and broad and diverse applications. Recently, we discovered that 1,2,4-triazolium-type PILs show enhanced performance profiles, which are due to stronger and more abundant supramolecular interactions ranging from hydrogen bonding to metal coordination, when compared with structurally similar imidazolium counterparts. This phenomenon in our view can be related to the smart hydrogen atoms (SHAs), that is, any proton that binds to the carbon in the N-heterocyclic cations of 1,2,4-triazolium-type PILs. The replacement of one carbon by an electron-withdrawing nitrogen atom in the broadly studied heterocyclic imidazolium ring will further polarize the C–H bond (especially for C5–H) of the resultant 1,2,4-triazolium cation and establish new chemical tools for materials design. For instance, the H-bond-donating strength of the SHA, as well as its Bro̷nsted acidity, is increased. Furthermore, polycarbene complexes can be readily formed even in the presence of weak or medium bases, which is by contrast rather challenging for imidazolium-type PILs. The combination of SHAs with the intrinsic features of heterocyclic cation-functionalized PILs (e.g., N-coordination capability and polymeric multibinding effects) enables new phenomena and therefore innovative materials applications.In this Account, recent progress on SHAs is presented. SHA-related applications in several research branches are highlighted together with the corresponding materials design at size scales ranging from nano- to micro- and macroscopic levels. At a nanoscopic level, it is possible to manipulate the interior and outer shapes and surface properties of PIL nanocolloids by adjusting the hydrogen bonds (H-bonds) between SHAs and water. Owing to the interplay of polycarbene structure, N-coordination, and the polymer multidentate binding of 1,2,4-triazolium-type PILs, metal clusters with controllable size at sub-nanometer scale were successfully synthesized and stabilized, which exhibited record-high catalytic performance in H2 generation via methanolysis of ammonia borane. At the microscopic level, SHAs are found to efficiently catalyze single crystal formation of structurally complex organics. Free protons in situ released from the SHAs serve as organocatalysts to activate formation of C–N bonds at room temperature in a series of imine-linked crystalline porous organics, such as organic cages, macrocycles and covalent organic frameworks; meanwhile the concurrent “salting-out” effect of PILs as polymers in solution accelerated the crystallization rate of product molecules by at least 1 order of magnitude. At the macroscopic scale, by finely regulating the supramolecular interactions of SHAs, a series of functional supramolecular porous polyelectrolyte membranes (SPPMs) with switchable pores and gradient cross-sectional structures were manufactured. These membranes demonstrate impressive figures of merit, ranging from chiral separation and proton recognition to switchable optical properties and real-time chemical reaction monitoring. Although the concept of SHAs is in the incipient stage of development, our successful examples of applications portend bright prospects for materials chemistry innovation.
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| 8. |
- Lu, Can, et al.
(författare)
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Semi Transparent Three-Dimensional Macroporous Quaternary Oxynitride Photoanodes for Photoelectrochemical Water Oxidation
- 2022
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Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 34:15, s. 6902-6911
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Tidskriftsartikel (refereegranskat)abstract
- Semi transparent three-dimensional macroporous (3DM) photoanodes based on quaternary oxynitrides have the potential to simultaneously realize superior light harvesting and efficient charge transfer in a tandem photoelectrochemical (PEC) cell. A 3DM CaTaO2N photoanode was prepared for the first time on a GaN/Al2O3 substrate via a chemical route, and it exhibits a high transmittance of > 60% in the wide solar spectrum and a photoresponse onset at -0.3 V versus the reversible hydrogen electrode (V-RHE) under simulated solar illumination. In particular, a plateau photocurrent density of 0.21 mA cm(-2) was achieved at a low potential of 0.4 V-RHE , which was 1.6-fold and more than 50-fold higher than a two-dimensional macroporous (2DM) CaTaO2N/GaN/Al2O3 photoanode and a conventional particle-based CaTaO2N/GaN/Al2O3 photoanode, respectively. The bicontinuous, interconnected pore structure within this 3DM film can improve charge carrier separation and collection by reducing the average diffusion distance for minority carriers toward the electrolyte. Optical measurements and simulations verified the enhanced sunlight harvesting in the 3DM photoanode, which was ascribed to the concentrated distribution of the electric field and multiple scattering. This study provides guidance for future synthesis of highly efficient semitransparent 3DM quaternary oxynitride-based photoanodes for a tandem PEC device.
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| 9. |
- Reiter, Manuel, et al.
(författare)
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Siloxane-Based Main-Chain Poly(ionic liquid)s via a Debus-Radziszewski Reaction
- 2022
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Ingår i: ACS Polymers Au. - : American Chemical Society (ACS). - 2694-2453. ; 2:2, s. 80-87
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Tidskriftsartikel (refereegranskat)abstract
- Herein, we synthesized a series of siloxane-based poly(ionic liquid)s (PILs) with imidazolium-type species in the main chain via the multicomponent Debus–Radziszewski reaction. We employed oligodimethylsiloxane diamine precursors to integrate flexible spacers in the polymer backbone and ultimately succeeded in obtaining main-chain PILs with low glass transition temperatures (Tgs) in the range of −40 to −18 °C. Such PILs were combined with conventional hydrophobic vinylimidazolium-based PILs for the fabrication of porous membranes via interpolyelectrolyte complexation with poly(acrylic acid), which leads to enhanced mechanical performance in the tensile testing measurements. This study will enrich the structure library of main-chain PILs and open up more opportunities for potential industrial applications of porous imidazolium-based membranes.
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| 10. |
- Tan, Liangxiao, et al.
(författare)
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Electrostatically cooperative host-in-host of metal cluster ⊂ ionic organic cages in nanopores for enhanced catalysis
- 2022
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- The construction of hierarchically nanoporous composite for high-performance catalytic application is still challenging. In this work, a series of host-in-host ionic porous materials are crafted by encapsulating ionic organic cages into a hyper-crosslinked, oppositely charged porous poly(ionic liquid) (PoPIL) through an ion pair-directed assembly strategy. Specifically, the cationic cage (C-Cage) as the inner host can spatially accommodate a functional Au cluster, forming a [Au⊂C-Cage+]⊂PoPIL− supramolecular composite. This dual-host molecular hierarchy enables a charge-selective substrate sorting effect to the Au clusters, which amplifies their catalytic activity by at least one order of magnitude as compared to Au confined only by C-Cage as the mono-host (Au⊂C-Cage+). Moreover, we demonstrate that such dual-host porous system can advantageously immobilize electrostatically repulsive Au⊂C-Cage+ and cationic ferrocene co-catalyst (Fer+) together into the same microcompartments, and synergistically speed up the enzyme-like tandem reactions by channelling the substrate to the catalytic centers via nanoconfinement.
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