Showing papers on "Solvent published in 2022"

Rational solvent molecule tuning for high-performance lithium metal battery electrolytes

Abstract: Electrolyte engineering improved cycling of Li metal batteries and anode-free cells at low current densities; however, high-rate capability and tuning of ionic conduction in electrolytes are desirable yet less-studied. Here, we design and synthesize a family of fluorinated-1,2-diethoxyethanes as electrolyte solvents. The position and amount of F atoms functionalized on 1,2-diethoxyethane were found to greatly affect electrolyte performance. Partially fluorinated, locally polar –CHF2 is identified as the optimal group rather than fully fluorinated –CF3 in common designs. Paired with 1.2 M lithium bis(fluorosulfonyl)imide, these developed single-salt-single-solvent electrolytes simultaneously enable high conductivity, low and stable overpotential, >99.5% Li||Cu half-cell efficiency (up to 99.9%, ±0.1% fluctuation) and fast activation (Li efficiency >99.3% within two cycles). Combined with high-voltage stability, these electrolytes achieve roughly 270 cycles in 50-μm-thin Li||high-loading-NMC811 full batteries and >140 cycles in fast-cycling Cu||microparticle-LiFePO4 industrial pouch cells under realistic testing conditions. The correlation of Li+–solvent coordination, solvation environments and battery performance is investigated to understand structure–property relationships. Cycling capability, especially at high rates, is limited for lithium metal batteries. Here the authors report electrolyte solvent design through fine-tuning of molecular structures to address the cyclability issue and unravel the electrolyte structure–property relationship for battery applications.

Rational solvent molecule tuning for high-performance lithium metal battery electrolytes

Abstract: Electrolyte engineering improved cycling of Li metal batteries and anode-free cells at low current densities; however, high-rate capability and tuning of ionic conduction in electrolytes are desirable yet less-studied. Here, we design and synthesize a family of fluorinated-1,2-diethoxyethanes as electrolyte solvents. The position and amount of F atoms functionalized on 1,2-diethoxyethane were found to greatly affect electrolyte performance. Partially fluorinated, locally polar –CHF2 is identified as the optimal group rather than fully fluorinated –CF3 in common designs. Paired with 1.2 M lithium bis(fluorosulfonyl)imide, these developed single-salt-single-solvent electrolytes simultaneously enable high conductivity, low and stable overpotential, >99.5% Li||Cu half-cell efficiency (up to 99.9%, ±0.1% fluctuation) and fast activation (Li efficiency >99.3% within two cycles). Combined with high-voltage stability, these electrolytes achieve roughly 270 cycles in 50-μm-thin Li||high-loading-NMC811 full batteries and >140 cycles in fast-cycling Cu||microparticle-LiFePO4 industrial pouch cells under realistic testing conditions. The correlation of Li+–solvent coordination, solvation environments and battery performance is investigated to understand structure–property relationships. Cycling capability, especially at high rates, is limited for lithium metal batteries. Here the authors report electrolyte solvent design through fine-tuning of molecular structures to address the cyclability issue and unravel the electrolyte structure–property relationship for battery applications.

Stimulus-responsive room temperature phosphorescence materials with full-color tunability from pure organic amorphous polymers

Abstract: Achieving stimulus-responsive ultralong room temperature phosphorescence (RTP) in organic materials especially with full-color tunable emissions is attractive and important but rarely reported. Here, a strategy was reported to realize stimulus-responsive RTP effect with color-tunable emissions by using water as solvent in the preparation process without any organic solvent through covalent linkage of arylboronic acids with different π conjugations and polymer matrix of polyvinyl alcohol. The yielded polymer films exhibit outstanding RTP performance (2.43 s). Furthermore, an excitation-dependent RTP film was obtained, and the afterglow color changes from blue to green, then to red as the excitation wavelength increases. The RTP property of all the above materials is sensitive to water and heat stimuli, because the rigidity of the system could be broken by water. Last, they were successfully applied in a multilevel information encryption and multicolor paper and ink.

HFIP in Organic Synthesis.

Abstract: 1,1,1,3,3,3-Hexafluoroisopropanol (HFIP) is a polar, strongly hydrogen bond-donating solvent that has found numerous uses in organic synthesis due to its ability to stabilize ionic species, transfer protons, and engage in a range of other intermolecular interactions. The use of this solvent has exponentially increased in the past decade and has become a solvent of choice in some areas, such as C-H functionalization chemistry. In this review, following a brief history of HFIP in organic synthesis and an overview of its physical properties, literature examples of organic reactions using HFIP as a solvent or an additive are presented, emphasizing the effect of solvent of each reaction.

A smart and responsive crystalline porous organic cage membrane with switchable pore apertures for graded molecular sieving

Abstract: Membranes with high selectivity offer an attractive route to molecular separations, where technologies such as distillation and chromatography are energy intensive. However, it remains challenging to fine tune the structure and porosity in membranes, particularly to separate molecules of similar size. Here, we report a process for producing composite membranes that comprise crystalline porous organic cage films fabricated by interfacial synthesis on a polyacrylonitrile support. These membranes exhibit ultrafast solvent permeance and high rejection of organic dyes with molecular weights over 600 g mol-1. The crystalline cage film is dynamic, and its pore aperture can be switched in methanol to generate larger pores that provide increased methanol permeance and higher molecular weight cut-offs (1,400 g mol-1). By varying the water/methanol ratio, the film can be switched between two phases that have different selectivities, such that a single, 'smart' crystalline membrane can perform graded molecular sieving. We exemplify this by separating three organic dyes in a single-stage, single-membrane process.

Weak Cation-solvent Interactions in Ether-based Electrolytes Stabilizing Potassium-ion Batteries.

Abstract: Conventional ether-based electrolytes exhibited low polarization voltage in potassium ion batteries, yet suffered from ion-solvent co-intercalation phenomenon in graphite anode, inferior potassium metal performance, and limited oxidation stability. Here, we revealed that weaken the cation-solvent interactions could suppress the co-intercalation behaviour, enhance the potassium metal performance, and improve the oxidation stability. Consequently, the graphite anode exhibits K + intercalation behaviour (K||graphite cell operates 200 cycles with 86.6% capacity retention), the potassium metal shows highly stable plating/stripping (K||Cu cell delivers 550 cycles with average Coulombic efficiency of 98.9%) and dendrite-free (symmetric K||K cell operates over 1400 hours) properties, and the electrolyte exhibits high oxidation stability up to 4.4 V. The ion-solvent interactions tuning strategy provides a promising method to develop high performance electrolytes and beyond.

Effect of Temperatures on Polyphenols during Extraction

Abstract: Background: Polyphenols are a set of bioactive compounds commonly found in plants. These compounds are of great interest, as they have shown high antioxidant power and are correlated to many health benefits. Hence, traditional methods of extraction such as solvent extraction, Soxhlet extraction and novel extraction technologies such as ultrasound-assisted extraction and subcritical water extraction (SWE) have been investigated for the extraction of polyphenols. Scope and Approach: Generally, for traditional extractions, the total phenolic content (TPC) is highest at an extraction temperature of 60–80 °C. For this reason, polyphenols are regularly regarded as heat-labile compounds. However, in many studies that investigated the optimal temperature for subcritical water extraction (SWE), temperatures as high as 100–200 °C have been reported. These SWE extractions showed extremely high yields and antioxidant capacities at these temperatures. This paper aimed to examine the relevant literature to identify and understand the mechanisms behind this discrepancy. Results: Thermal degradation is the most common explanation for the degradation of polyphenols. This may be the case for specific or sub-groups of phenolic acids. The different extraction temperatures may have also impacted the types of polyphenols extracted. At high extraction temperatures, the formation of new compounds known as Maillard reaction products may also influence the extracted polyphenols. The selection of source material for extraction, i.e., the plant matrix, and the effect of extraction conditions, i.e., oxidation and light exposure, are also discussed. The overestimation of total phenolic content by the Folin–Ciocâlteu assay is also discussed. There is also a lack of consensus in TPC’s correlation to antioxidant activity.

A Self-Supporting Covalent Organic Framework Separator with Desolvation Effect for High Energy Density Lithium Metal Batteries

Abstract: Covalent organic frameworks (COF) displayed strong affinity between COF and Li+ in terms of previous works. However, the relationship of COF and solvent molecules in the electrolyte was exclusive. Herein, a self-supporting COF separator (TPB-BD(OH)2-COF) was synthesized and served as a separator in lithium metal batteries. The formation of hydrogen bond network is due to the interaction of hydroxyl functional group (−OH) in TPB-BD(OH)2-COF and −OH···F and −OH···O in PF6–, EC and EMC within solvent sheath to achieve the desolvation process and realize more aggregative electrolyte, thus reducing the free solvent and lithium metal side effects. Therefore, the full cell assembled with self-supporting COF displayed superior cycling stability with a reversible capacity of 114.3 mAh g–1 after 335 cycles at a current density of 1C and a capacity of 5 mAh cm–2. Moreover, the COF separator can perform well even in extreme environments (temperature 60 °C).

A universal co-solvent dilution strategy enables facile and cost-effective fabrication of perovskite photovoltaics

Abstract: Cost management and toxic waste generation are two key issues that must be addressed before the commercialization of perovskite optoelectronic devices. We report a groundbreaking strategy for eco-friendly and cost-effective fabrication of highly efficient perovskite solar cells. This strategy involves the usage of a high volatility co-solvent, which dilutes perovskite precursors to a lower concentration (<0.5 M) while retaining similar film quality and device performance as a high concentration (>1.4 M) solution. More than 70% of toxic waste and material cost can be reduced. Mechanistic insights reveal ultra-rapid evaporation of the co-solvent together with beneficial alteration of the precursor colloidal chemistry upon dilution with co-solvent, which in-situ studies and theoretical simulations confirm. The co-solvent tuned precursor colloidal properties also contribute to the enhancement of the stability of precursor solution, which extends its processing window thus minimizing the waste. This strategy is universally successful across different perovskite compositions, and scales from small devices to large-scale modules using industrial spin-coating, potentially easing the lab-to-fab translation of perovskite technologies.

Fabrication of highly hydrophobic or superhydrophobic electrospun PVA and agar/PVA membrane materials for efficient and selective oil/water separation

Abstract: Efficient and selective separation of oily substances from water or oil-water emulsions is a very important issue in the treatment processes of oily wastewater to prevent environmental pollution. In this study, for the effective treatment of water polluted with oils or organic solvents, highly hydrophobic or superhydrophobic water-insoluble eco-friendly electrospun poly(vinyl alcohol) (PVA) and agar/PVA membrane materials were successfully prepared via (i) electrospinning technique, (ii) cross-linking approach with glutaraldehyde and (iii) coating process with methyltrichlorosilane (MTCS) in petroleum ether. Membrane materials were characterized with contact angle, water solubility, FT-IR, SEM and XPS measurements. Water contact angle (WCA) of PVA and agar/PVA membranes was measured as 148.1° and 150.1°, respectively. Membrane materials were able to separate selectively the toluene and chloroform droplets from water and showed good oil and organic solvent absorption capacity (5.5–22.8 g g−1 for PVA membrane and 4.1–21.7 g g−1 for agar/PVA membrane). For chloroform-water mixture (1:1, v/v), the flux value of PVA and agar/PVA membranes was determined to be 1234 L m−2 h−1 bar−1 and 1136 L m−2 h−1 bar−1, respectively. In addition, the developed membrane materials displayed excellent separation efficiency (≥99.9%) for chloroform-water mixture. PVA and agar/PVA membranes exhibited a good water-in-oil/organic solvent (water-in-toluene, water-in-chloroform and water-in-diesel) emulsion separation performance (≥97.5%). PVA and agar/PVA membrane materials prepared in this study are environmentally friendly and have an affordable price and the potential in practical applications for the treatment of wastewater polluted with oils and organic solvents and for the separation of oily substance-water mixtures.

Author Correction: A universal co-solvent dilution strategy enables facile and cost-effective fabrication of perovskite photovoltaics

Abstract: Cost management and toxic waste generation are two key issues that must be addressed before the commercialization of perovskite optoelectronic devices. We report a groundbreaking strategy for eco-friendly and cost-effective fabrication of highly efficient perovskite solar cells. This strategy involves the usage of a high volatility co-solvent, which dilutes perovskite precursors to a lower concentration (<0.5 M) while retaining similar film quality and device performance as a high concentration (>1.4 M) solution. More than 70% of toxic waste and material cost can be reduced. Mechanistic insights reveal ultra-rapid evaporation of the co-solvent together with beneficial alteration of the precursor colloidal chemistry upon dilution with co-solvent, which in-situ studies and theoretical simulations confirm. The co-solvent tuned precursor colloidal properties also contribute to the enhancement of the stability of precursor solution, which extends its processing window thus minimizing the waste. This strategy is universally successful across different perovskite compositions, and scales from small devices to large-scale modules using industrial spin-coating, potentially easing the lab-to-fab translation of perovskite technologies.

What is the Real Origin of the Activity of Fe-N-C Electrocatalysts in the O2 Reduction Reaction? Critical Roles of Coordinating Pyrrolic N and Axially Adsorbing Species.

Abstract: Fe-N-C electrocatalysts have emerged as promising substitutes for Pt-based catalysts for the oxygen reduction reaction (ORR). However, their real catalytic active site is still under debate. The underlying roles of different types of coordinating N including pyridinic and pyrrolic N in catalytic performance require thorough clarification. In addition, how to understand the pH-dependent activity of Fe-N-C catalysts is another urgent issue. Herein, we comprehensively studied 13 different N-coordinated FeNxC configurations and their corresponding ORR activity through simulations which mimic the realistic electrocatalytic environment on the basis of constant-potential implicit solvent models. We demonstrate that coordinating pyrrolic N contributes to a higher activity than pyridinic N, and pyrrolic FeN4C exhibits the highest activity in acidic media. Meanwhile, the in situ active site transformation to *O-FeN4C and *OH-FeN4C clarifies the origin of the higher activity of Fe-N-C in alkaline media. These findings can provide indispensable guidelines for rational design of better durable Fe-N-C catalysts.

Deep Eutectic Solvent as Green Solvent in Extraction of Biological Macromolecules: A Review

Abstract: Greater awareness of environmental sustainability has driven many industries to transition from using synthetic organic solvents to greener solvents in their manufacturing. Deep eutectic solvents (DESs) have emerged as a highly promising category of green solvents with well-demonstrated and wide-ranging applications, including their use as a solvent in extraction of small-molecule bioactive compounds for food and pharmaceutical applications. The use of DES as an extraction solvent of biological macromolecules, on the other hand, has not been as extensively studied. Thereby, the feasibility of employing DES for biomacromolecule extraction has not been well elucidated. To bridge this gap, this review provides an overview of DES with an emphasis on its unique physicochemical properties that make it an attractive green solvent (e.g., non-toxicity, biodegradability, ease of preparation, renewable, tailorable properties). Recent advances in DES extraction of three classes of biomacromolecules—i.e., proteins, carbohydrates, and lipids—were discussed and future research needs were identified. The importance of DES’s properties—particularly its viscosity, polarity, molar ratio of DES components, and water addition—on the DES extraction’s performance were discussed. Not unlike the findings from DES extraction of bioactive small molecules, DES extraction of biomacromolecules was concluded to be generally superior to extraction using synthetic organic solvents.

Two Compatible Acceptors as an Alloy Model with a Halogen-Free Solvent for Efficient Ternary Polymer Solar Cells.

Abstract: A ternary strategy of halogen-free solvent processing can open up a promising pathway for the preparation of polymer solar cells (PSCs) on a large scale and can effectively improve the power conversion efficiency with an appropriate third component. Herein, the green solvent o-xylene (o-XY) is used as the main solvent, and the non-fullerene acceptor Y6-DT-4F as the third component is introduced into the PBB-F:IT-4F binary system to broaden the spectral absorption and optimize the morphology to achieve efficient PSCs. The third component, Y6-DT-4F, is compatible with IT-4F and can form an "alloy acceptor", which can synergistically optimize the photon capture, carrier transport, and collection capabilities of the ternary device. Meanwhile, Y6-DT-4F has strong crystallinity, so when introduced into the binary system as the third component can enhance the crystallization, which is conducive to the charge transport. Consequently, the optimal ternary system based on PBB-F:IT-4F:Y6-DT-4F achieved an efficiency of 15.24%, which is higher than that of the binary device based on PBB-F:IT-4F (13.39%).

Large-Area 2D Covalent Organic Framework Membranes with Tunable Single-Digit Nanopores for Predictable Mass Transport.

Abstract: The potential of covalent organic frameworks (COFs) for molecular separations remains unrealized because of challenges transforming nanoscale COF materials into large-area functional COF membranes. Herein, we report the synthesis of large-area (64 cm2), ultrathin (24 nm), β-ketoenamine-linked 2D COFs using a facile interfacial polymerization technique. Angstrom-level control over single-digit nanopore size (1.4-2.0 nm) is achieved by direct integration of variable-length monomers. We apply these techniques to fabricate a series of large-area 2D COF membranes with variable thicknesses, pore sizes, and supporting materials. Tunable 2D COF properties enable control over COF membrane mass transport, resulting in high solvent fluxes and sharp molecular weight cutoffs. For organic solvent nanofiltration, the 2D COF membranes demonstrate an order-of-magnitude greater permeance than the state-of-the-art commercial polymeric membrane. We apply continuum models to quantify the dominance of pore passage resistance to mass transport over pore entrance resistance. A strong linear correlation between single-digit nanopore tortuosity and 2D COF thickness enables solvent fluxes to be predicted directly from solvent viscosity and COF membrane properties. Solvent-nanopore interactions characterized by the membrane critical interfacial tension also appear to influence mass transport. The pore flow transport model is validated by predicting the flux of a 52 nm thick COF membrane.

Weak Cation–Solvent Interactions in Ether‐Based Electrolytes Stabilizing Potassium‐ion Batteries

Abstract: Conventional ether-based electrolytes exhibited low polarization voltage in potassium ion batteries, yet suffered from ion-solvent co-intercalation phenomenon in graphite anode, inferior potassium metal performance, and limited oxidation stability. Here, we revealed that weaken the cation-solvent interactions could suppress the co-intercalation behaviour, enhance the potassium metal performance, and improve the oxidation stability. Consequently, the graphite anode exhibits K + intercalation behaviour (K||graphite cell operates 200 cycles with 86.6% capacity retention), the potassium metal shows highly stable plating/stripping (K||Cu cell delivers 550 cycles with average Coulombic efficiency of 98.9%) and dendrite-free (symmetric K||K cell operates over 1400 hours) properties, and the electrolyte exhibits high oxidation stability up to 4.4 V. The ion-solvent interactions tuning strategy provides a promising method to develop high performance electrolytes and beyond.

Revisiting the Physicochemical Properties and Applications of Deep Eutectic Solvents

Abstract: Recently, deep eutectic solvent (DES) or ionic liquid (IL) analogues have been considered as the newest green solvent, demonstrating the potential to replace harsh volatile organic solvents. DESs are mainly a combination of two compounds: hydrogen bond acceptor (HBA) and hydrogen bond donor (HBD), which have the ability to interact through extensive hydrogen bonds. A thorough understanding of their physicochemical properties is essential, given their successful applications on an industrial scale. The appropriate blend of HBA to HBD can easily fine-tune DES properties for desired applications. In this context, we have reviewed the basic information related to DESs, the two most studied physicochemical properties (density and viscosity), and their performance as a solvent in (i) drug delivery and (ii) extraction of biomolecules. A broader approach of various factors affecting their performance has been considered, giving a detailed picture of the current status of DESs in research and development.

Deep eutectic solvents in liquid-phase microextraction: contribution to green chemistry

Abstract: In recent years, the search for the principles of green chemistry in analytical methods has grown considerably. In green analytical chemistry, solvents occupy an essential place. Some criteria are necessary for a solvent to be qualified as a green medium, such as availability, low toxicity, biodegradability, and low cost. So far, the number of green solvents available is quite limited. Many extraction techniques have emerged as alternatives to conventional extraction procedures, using green solvents. A new group of solvents known as deep eutectic solvents (DESs) has emerged as a new and promising alternative for substituting traditional solvents. DESs attract attention due to their peculiar characteristics: eco-friendly, inexpensive, and simple to obtain. This work presents a critical review involving DESs in liquid-phase microextraction (LPME) and their contributions to green chemistry.

Temperature- and solvent-induced reversible single-crystal-to-single-crystal transformations of TbIII-based MOFs with excellent stabilities and fluorescence sensing properties toward drug molecules

Abstract: Recently, single-crystal-to-single-crystal conversion has been a hot topic in the field of metal-organic framework (MOF) materials, which could improve the stability and properties due to the structural change. A new...

Deep eutectic solvents in liquid-phase microextraction: Contribution to green chemistry

Abstract: In recent years, the search for the principles of green chemistry in analytical methods has grown considerably. In green analytical chemistry, solvents occupy an essential place. Some criteria are necessary for a solvent to be qualified as a green medium, such as availability, low toxicity, biodegradability, and low cost. So far, the number of green solvents available is quite limited. Many extraction techniques have emerged as alternatives to conventional extraction procedures, using green solvents. A new group of solvents known as deep eutectic solvents (DESs) has emerged as a new and promising alternative for substituting traditional solvents. DESs attract attention due to their peculiar characteristics: eco-friendly, inexpensive, and simple to obtain. This work presents a critical review involving DESs in liquid-phase microextraction (LPME) and their contributions to green chemistry.