Showing papers on "Ionic liquid published in 2021"

High-Efficiency Perovskite Solar Cells with Imidazolium-Based Ionic Liquid for Surface Passivation and Charge Transport.

Abstract: Surface defects have been a key constraint for perovskite photovoltaics. Herein, 1,3-dimethyl-3-imidazolium hexafluorophosphate (DMIMPF6 ) ionic liquid (IL) is adopted to passivate the surface of a formamidinium-cesium lead iodide perovskite (Cs0.08 FA0.92 PbI3 ) and also reduce the energy barrier between the perovskite and hole transport layer. Theoretical simulations and experimental results demonstrate that Pb-cluster and Pb-I antisite defects can be effectively passivated by [DMIM]+ bonding with the Pb2+ ion on the perovskite surface, leading to significantly suppressed non-radiative recombination. As a result, the solar cell efficiency was increased to 23.25 % from 21.09 %. Meanwhile, the DMIMPF6 -treated perovskite device demonstrated long-term stability because the hydrophobic DMIMPF6 layer blocked moisture permeation.

Preparation of cellulose-based hydrogel: a review

Abstract: This paper reviews the preparation of hydrogel based on cellulose and its derivatives. Cellulose is the most abundant natural organic polymer on earth. To date, the exploitation of cellulose has been studied in various applications. However, cellulose has low solubility in water and most organic solvents. Thus, specific solvent systems such as NaOH/urea, NaOH/thiourea, lithium chloride, and ionic liquids need to be employed to vary cellulose application. The hydrogel is a 3D network structure that can retain a tremendous amount of water and highly dependent on the crosslinking property. It is important to use a compatible technique for a specific purpose. The paper discusses the materials and crosslinking techniques via chemical, physical, and polymerization, to produce hydrogels from dissolved cellulose and its derivatives.

Carbon dioxide capture using liquid absorption methods: a review

Abstract: Anthropogenic emissions of greenhouse gases into the atmosphere is inducing global warming, ocean acidification, polar ice melting, rise in sea level, droughts and hurricanes, thus threatening human health and the global economy. Therefore, there is a need to develop cost-effective technologies for CO2 capture. For instance, solution absorption is promising due to a large processing capacity, high flexibility and reliability, and rich experience in engineering applications. Nonetheless, actual commercial solutions, solvents and processes for CO2 capture suffer from slow reaction kinetics, low absorption capacity, high-energy consumption, susceptibility to corrosion, toxicity, low stability and high costs. Therefore, current research focuses on developing more economical, effective, green and sustainable technologies. Here we review 2015–2020 findings on CO2 capture using liquid absorption methods. Methods are based on various solutions, solvents and processes such as carbonate solution, ammonia solution, amine-based solution, ionic liquid, amino acid salt, phase changing absorbent, microcapsulated and membrane absorption, nanofluids and phenoxide salt solution. We discuss absorption performance, absorption mechanism, enhancement pathways and challenges. Amine- and NH3-based absorbents are widely used, yet they are limited by high regeneration energy, corrosiveness and degradation, reagent loss and secondary pollution caused by NH3 escape. Phase changing absorbents are getting more attention due to their lower cost and lower energy penalty. The incorporation of membrane and microencapsulation technologies to absorbing solvents could enhance CO2 absorption performance by reducing corrosion and increasing selectivity. Adding nanoparticles to solvents could improve CO2 absorption performance and reduce energy requirement. Besides, solvent blends and promoter-improved solvents performed better than single and non-promoted solvents because they combine the benefits of individual solvents and promoters.

Light‐Responsive, Reversible Emulsification and Demulsification of Oil‐in‐Water Pickering Emulsions for Catalysis

Abstract: Pickering emulsions are an excellent platform for interfacial catalysis. However, developing simple and efficient strategies to achieve product separation and catalyst and emulsifier recovery is still a challenge. Herein, we report the reversible transition between emulsification and demulsification of a light-responsive Pickering emulsion, triggered by alternating between UV and visible light irradiation. The Pickering emulsion is fabricated from Pd-supported silica nanoparticles, azobenzene ionic liquid surfactant, n-octane, and water. This phase behavior is attributed to the adsorption of azobenzene ionic liquid surfactant on the surface of the nanoparticles and the light-responsive activity of ionic liquid surfactant. The Pickering emulsion can be used as a microreactor that enables catalytic reaction, product separation as well as emulsifier and catalyst recycling. Catalytic hydrogenation of unsaturated hydrocarbons at room temperature and atmospheric pressure has been performed in this system to demonstrate product separation and emulsifier and catalyst re-use.

Ionic liquid-assisted synthesis of nickel cobalt phosphide embedded in N, P codoped-carbon with hollow and folded structures for efficient hydrogen evolution reaction and supercapacitor

Abstract: Herein, bimetallic nickel cobalt phosphide and N, P-doped carbon composite (NiCoP/NPC) with folded and hollow spherical structures were first synthesized using a facile ionic liquid-assisted approach. The abundant folds increased the specific surface area by five times compared to the sample without adding ionic liquid. The carbon composites doped with N and P atoms lead to faster electron transfer and more active sites, as verified by density functional theory (DFT). When used as a catalyst, the overpotentials for HER at a current density of 10 mA cm−2 were 108, 128 and 106 mV in acidic, alkaline and neutral media, respectively. Moreover, the optimally structured also showed superior electrochemical performance in an asymmetric supercapacitor with an energy density as high as 26.8 Wh kg−1 at the power density of 7973.0 W kg−1. This study offers a valuable reference for the rational design and synthesis to improved composite surface area and element-doping.

MOF-Directed Synthesis of Crystalline Ionic Liquids with Enhanced Proton Conduction.

Abstract: Arranging ionic liquids (ILs) with long-range order can not only enhance their performance in a desired application, but can also help elucidate the vital between structure and properties. However, this is still a challenge and no example has been reported to date. Herein, we report a feasible strategy to achieve a crystalline IL via coordination self-assembly based reticular chemistry. IL1 MOF, was prepared by designing an IL bridging ligand and then connecting them with metal clusters. IL1 MOF has a unique structure, where the IL ligands are arranged on a long-range ordered framework but have a labile ionic center. This structure enables IL1 MOF to break through the typical limitation where the solid ILs have lower proton conductivity than their counterpart bulk ILs. IL1 MOF shows 2-4 orders of magnitude higher proton conductivity than its counterpart IL monomer across a wide temperature range. Moreover, by confining the IL within ultramicropores (<1 nm), IL1 MOF suppresses the liquid-solid phase transition temperatures to lower than -150 °C, allowing it to function with high conductivity in a subzero temperature range.

Antimicrobial ionic liquid‐based materials for biomedical applications

Abstract: Excessive and unwarranted administration of antibiotics has invigorated the evolution of multidrug-resistant microbes. There is, therefore, an urgent need for advanced active compounds. Ionic liquids with short-lived ion-pair structures are highly tunable and have diverse applications. Apart from their unique physicochemical features, the newly discovered biological activities of ionic liquids have fascinated biochemists, microbiologists, and medical scientists. In particular, their antimicrobial properties have opened new vistas in overcoming the current challenges associated with combating antibiotic-resistant pathogens. Discussions regarding ionic liquid derivatives in monomeric and polymeric forms with antimicrobial activities are presented here. The antimicrobial mechanism of ionic liquids and parameters that affect their antimicrobial activities, such as chain length, cation/anion type, cation density, and polymerization, are considered. The potential applications of ionic liquids in the biomedical arena, including regenerative medicine, biosensing, and drug/biomolecule delivery, are presented to stimulate the scientific community to further improve the antimicrobial efficacy of ionic liquids.

Preparation of Hierarchical Porous Activated Carbon from Banana Leaves for High-performance Supercapacitor: Effect of Type of Electrolytes on Performance

Abstract: We demonstrate a facile efficient way to fabricate activated carbon nanosheets (ACNSs) consisting of hierarchical porous carbon materials. Simply heating banana leaves with K2 CO3 produce ACNSs having a unique combination of macro-, meso- and micropores with a high specific surface area of ∼1459 m2 g-1 . The effects of different electrolytes on the electrochemical supercapacitor performance and stability of the ACNSs are tested using a two-electrode system. The specific capacitance (Csp ) values are 55, 114, and 190 F g-1 in aqueous 0.5 M sodium sulfate, organic 1 M tetraethylammonium tetrafluoroborate in acetonitrile, and pure ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6 ]) electrolytes, respectively. The ACNSs also shows the largest potential window of 3.0 V, the highest specific energy (59 Wh kg-1 ) and specific power (750 W kg-1 ) in [BMIM][PF6 ]. A mini-prototype device is prepared to demonstrate the practicality of the ACNSs.

Enhancing oxygen reduction electrocatalysis by tuning interfacial hydrogen bonds

Abstract: Proton activity at the electrified interface is central to the kinetics of proton-coupled electron transfer (PCET) reactions for making chemicals and fuels. Here we employ a library of protic ionic liquids in an interfacial layer on platinum and gold to alter local proton activity, where the intrinsic oxygen-reduction reaction (ORR) activity is enhanced up to fivefold, exhibiting a volcano-shaped dependence on the pKa of the ionic liquid. The enhanced ORR activity is attributed to strengthened hydrogen bonds between ORR products and ionic liquids with comparable pKas, resulting in favourable PCET kinetics. This proposed mechanism is supported by in situ surface-enhanced Fourier-transform infrared spectroscopy and our simulation of PCET kinetics based on computed proton vibrational wavefunctions at the hydrogen-bonding interface. These findings highlight opportunities for using non-covalent interactions between hydrogen-bonded structures and solvation environments at the electrified interface to tune the kinetics of ORR and beyond. Understanding the role of hydrogen bonds at the electrode interface is important for controlling the kinetics of the oxygen-reduction reaction. Here the authors modify gold and platinum surfaces with a series of protic ionic liquids to show that pKa can be used to optimize proton-coupled electron transfer through hydrogen bonding.

Solid-state rigid-rod polymer composite electrolytes with nanocrystalline lithium ion pathways.

Abstract: A critical challenge for next-generation lithium-based batteries lies in development of electrolytes that enable thermal safety along with the use of high-energy-density electrodes. We describe molecular ionic composite electrolytes based on an aligned liquid crystalline polymer combined with ionic liquids and concentrated Li salt. This high strength (200 MPa) and non-flammable solid electrolyte possesses outstanding Li+ conductivity (1 mS cm−1 at 25 °C) and electrochemical stability (5.6 V versus Li|Li+) while suppressing dendrite growth and exhibiting low interfacial resistance (32 Ω cm2) and overpotentials (≤120 mV at 1 mA cm−2) during Li symmetric cell cycling. A heterogeneous salt doping process modifies a locally ordered polymer–ion assembly to incorporate an inter-grain network filled with defective LiFSI and LiBF4 nanocrystals, strongly enhancing Li+ conduction. This modular material fabrication platform shows promise for safe and high-energy-density energy storage and conversion applications, incorporating the fast transport of ceramic-like conductors with the superior flexibility of polymer electrolytes. Developing safe electrolytes compatible with high-energy-density electrodes is key for the next generation of lithium-based batteries. Stable solid-state rigid-rod polymer composite electrolytes with nanocrystalline lithium ion pathways are now proposed.

Sulfonic Acid and Ionic Liquid Functionalized Covalent Organic Framework for Efficient Catalysis of the Biginelli Reaction

Abstract: A quinoline-linked and ionic liquid-decorated covalent organic framework was prepared by incorporation of a multicomponent Povarov reaction and postsynthetic modification. The imidazolium and sulfonic acid-decorated COF-IM-SO3H can be a highly efficient Bronsted acid catalyst to promote the Biginelli reaction under solvent-free conditions in a heterogeneous way. In addition, a scaled-up Biginelli reaction has been readily realized over a COF-IM-SO3H@chitosan aerogel-based cup reactor.

Recent Advances in Ionic Liquids in Biomedicine

Abstract: The use of ionic liquids and deep eutectic solvents in biomedical applications has grown dramatically in recent years due to their unique properties and their inherent tunability. This review will introduce ionic liquids and deep eutectics and discuss their biomedical applications, namely solubilization of drugs, creation of active pharmaceutical ingredients, delivery of pharmaceuticals through biological barriers, stabilization of proteins and other nucleic acids, antibacterial agents, and development of new biosensors. Current challenges and future outlooks are discussed, including biocompatibility, the potential impact of the presence of impurities, and the importance of understanding the microscopic interactions in ionic liquids in order to design task-specific solvents.

Inorganic Synthesis Based on Reactions of Ionic Liquids and Deep Eutectic Solvents.

Abstract: Ionic liquids and deep eutectic solvents are of growing interest as solvents for the resource-efficient synthesis of inorganic materials. This Review covers chemical reactions of various deep eutectic solvents and types of ionic liquids, including metal-containing ionic liquids, [BF4 ]- - or [PF6 ]- -based ionic liquids, basic ionic liquids, and chalcogen-containing ionic liquids. Cases in which cations, anions, or both are incorporated into the final products are also included. The purpose of this Review is to raise caution about the chemical reactivity of ionic liquids and deep eutectic solvents and to establish a guide for their proper use.

Metal-Based Ionic Liquids in Oxidative Desulfurization: A Critical Review

Abstract: Ionic liquids (ILs) as novel functional desulfurization materials have attracted increasing attentions. Metal-based ionic liquids (MILs) are classified into three types of metal chloride ILs, metal oxide ILs, and metal complex ILs based on the definition and basic structure of MILs in this critical review. On the basis of the properties of ILs such as structure designability, super dissolution performance, good thermal and chemical stability, nonflammability, and wide electrochemical window, MILs exhibit unique advantages on hydrophobicity, oxidation performance, and Bronsted-Lewis acidity. Therefore, MILs possess both the absorption and oxidation centers for the intramolecular adsorption and oxidation to improve the oxidative desulfurization (ODS) process. During the novel nonaqueous wet oxidative desulfurization process (Nasil), H2S can be oxidized into elemental sulfur with hydrophobic MILs, which can be regenerated by oxygen for recycle, to solve the problems of low sulfur capacity, low sulfur quality, and severe secondary pollution in the aqueous Lo-Cat wet oxidative desulfurization process. Another outstanding feature of MILs in ODS is biomimetic catalysis, which has the function of activating molecular oxygen and improving the oxidation performance. Metal oxide ILs and metal complex ILs are used in combination with hydrogen peroxide or oxygen with the existing water to generate a Fenton-like reaction to convert hydrophobic organic sulfur or SO2 into hydrophilic sulfoxide/sulfone or sulfur acid, respectively. However, the corrosion of Cl- to the equipment and emulsification phenomenon in the extraction process of sulfoxide/sulfone separation still need further study. Furthermore, the promising strategies to construct highly efficient and green desulfurization processes for large-scale applications are provided.

Ionic Liquid-Based Electrolytes for Aluminum/Magnesium/Sodium-Ion Batteries

Abstract: Developing post-lithium-ion battery technology featured with high raw material abundance and low cost is extremely important for the large-scale energy storage applications, especially for the metal-based battery systems such as aluminum, sodium, and magnesium ion batteries. However, their developments are still in early stages, and one of the major challenges is to explore a safe and reliable electrolyte. An ionic liquid-based electrolyte is attractive and promising for developing safe and nonflammable devices with wide temperature ranges owing to their several unique properties such as ultralow volatility, high ionic conductivity, good thermal stability, low flammability, a wide electrochemical window, and tunable polarity and basicity/acidity. In this review, the recent emerging limitations and strategies of ionic liquid-based electrolytes in the above battery systems are summarized. In particular, for aluminum-ion batteries, the interfacial reaction between ionic liquid-based electrolytes and the electrode, the mechanism of aluminum storage, and the optimization of electrolyte composition are fully discussed. Moreover, the strategies to solve the problems of electrolyte corrosion and battery system side reactions are also highlighted. Finally, a general conclusion and a perspective focusing on the current development limitations and directions of ionic liquid-based electrolytes are proposed along with an outlook. In order to develop novel high-performance ionic liquid electrolytes, we need in-depth understanding and research on their fundamentals, paving the way for designing next-generation products.

One-step multiple-site integration strategy for CO2 capture and conversion into cyclic carbonates under atmospheric and cocatalyst/metal/solvent-free conditions

Abstract: The capture of CO2 and subsequent conversion into high value-added chemicals under atmospheric conditions is an on-going challenge. This work reports a facile multiple-site integration strategy for the capture of low-concentration CO2 and subsequent cocatalyst/metal/solvent-free coupling with epoxides to synthesize cyclic carbonates under atmospheric conditions. Through the one-step integration of commonly-used imidazolium ionic liquids (ILs) and quaternary ammonium salt, porous polyILs with acidic/basic moieties (–NH2, –COOH), active cations (imidazolium, quaternary ammonium) and nucleophilic counterions (Br–, Cl–, OH–) have been fabricated. The cooperation of nucleophilicity, basicity and acidity, which is critical for the activation of CO2 and epoxides, has been flexibly modulated via regulating the type and content of the multiple-sites. The polyILs show good low-concentration CO2 affinity, high catalytic activity under atmospheric conditions, efficient recyclability and excellent tolerance for a variety of epoxides, and the new strategy developed shows great potential for practical applications in low-energy fixation of CO2.

Cation‐Assisted Lithium Ion Transport for High Performance PEO‑based Ternary Solid Polymer Electrolytes

Abstract: N-alkyl-N-alkyl pyrrolidinium-based ionic liquids (ILs) are promising candidates as non-flammable plasticizers for lowering the operation temperature of poly(ethylene oxide) (PEO)-based solid polymer electrolytes (SPEs), but they present limitations in terms of lithium-ion transport, such as a much lower lithium transference number. Thus, a pyrrolidinium cation was prepared with an oligo(ethylene oxide) substituent with seven repeating units. We show, by a combination of experimental characterizations and simulations, that the cation's solvating properties allow faster lithium-ion transport than alkyl-substituted analogues when incorporated in SPEs. This proceeds not only by accelerating the conduction modes of PEO, but also by enabling new conduction modes linked to the solvation of lithium by a single IL cation. This, combined with favorable interfacial properties versus lithium metal, leads to significantly improved performance on lithium-metal polymer batteries.