Facile Ionic Liquid Research Articles

Ionic Liquid Passivation for High‐Performance Sky‐Blue Quasi‐2D Perovskite Light‐Emitting Diodes

AbstractGreat progress has been made in high‐performance perovskite light‐emitting diodes (PeLEDs). However, the external quantum efficiency (EQE) of blue PeLEDs still lags. Particularly, defects are inevitable in solution‐processed perovskite films, which inhibit the efficient radiative recombination in blue PeLEDs. Herein, a facile ionic liquid (IL, 1,3‐dimethyl‐3‐imidazolium hexafluorophosphate) post‐treatment on the as‐fabricated quasi‐2D perovskite film is reported, to passivate the uncoordinated Pb through the strong interaction with IL. The IL‐assisted perovskite film demonstrates a great enhancement of radiative recombination efficiency, and the photoluminescence quantum yield of the film increases from 35.7% to 74.6%. IL post‐treatment also adjusts the energy level of perovskite film and enhances the hole injection in PeLED. As a result, the peak EQE of the sky‐blue quasi‐2D PeLED is improved from 4.0% to 9.0%, while the turn‐on voltage is reduced from 3.3 to 3.0 V. This work contributes to a feasible and effective approach for improving the quality of blue quasi‐2D perovskites and enhancing the efficiency of blue PeLEDs.

Atomic-level modulation of local coordination environment at Fe single-atom sites for enhanced oxygen reduction

Single-atom catalysts (SACs) have aroused extensive attention due to their ultrahigh activity and selectivity. However, precisely regulating and designing the coordination microenvironment of SACs to optimize the catalytic efficiency remains a great challenge. Here, a facile ionic liquid (IL) modification strategy is creatively proposed to obtain N and P dual-coordinated Fe single atoms with N unsaturated coordination on pre-designed FeSAC-N4/C sites. The using a hydrophobic IL can alter the binding affinity of O2, maintain a higher O2 concentration at the catalyst interface, and protect Fe single atom sites from surface oxidation and methanol toxicity. Theoretical calculation indicates that this unique coordination and the N vacancy can tailor the electronic structure of the metal atoms and alter the charge distribution at the coordination structures, thus improving the oxygen reduction reaction performance. This study offers an effective approach for accurately controlling the coordination electronic structure and interface environment of SACs at room temperature.

A general and facile solution approach for deposition of high-quality metal oxide charge transport layers

Metal oxide charge transport layers (CTLs) are significant components for fabricating high-performance thin film solar cells. Generally, sol-gel methods have been widely used to deposit high-quality metal oxide CTLs, but they usually suffer from the choices of solvents, ligands and metal precursors. Here we report a general and facile ionic liquid (n-butylammonium butyrate) approach to prepare V2O5, MoO3, WO3, NiO, ZnO and SnO2 thin films, which exhibits strong dissolving ability and good film-forming property. The thermal volatilization of ionic liquid is mild, which provides a slow and stable decomposition process of metal compounds and favors the formation of smooth and compact CTLs. All thin films are highly transparent in the visual range from the optical transmittance spectra and suitable to be CTLs in photovoltaic devices. Encouragingly, we have received the efficiencies of 15.06% and 13.38% based on the area of 0.09 and 1.21 cm2 (NiO as the hole transport layer), and 19.13% and 16.71% based on the area of 0.09 and 1.21 cm2 (SnO2 as the electron transport layer), which are obviously higher than those of devices prepared by traditional sol-gel methods.

Ionic Liquid-Mediated Mass Transport Channels for Ultrahigh Rate Lithium-Ion Batteries.

Excellent mass transport capability is indispensable to building a high-power lithium-ion battery (LIB) system. Nanomaterials with enhanced electrochemical properties have been used for next-generation high-performance LIBs. However, due to the high surface free energy, nanomaterials tend to form agglomeration. The resulting insufficient mass transport channels limit the high rate performance of nanomaterials. Here, we increase the electrolyte accessibility of nanomaterials through a facile ionic liquid (IL) mediation method. The fluidity and affinity enable the IL to infiltrate into the interstitials of nanomaterial aggregations under capillary force, enhancing the electrochemically active contact area and ensuring rapid mass transport. As a proof of concept, IL-mediated LiFePO4 electrodes delivered extraordinary rate performance (112 and 95 mAh g-1 at 200 and 300 C, respectively). In terms of simplicity, the IL mediation can be used as a general strategy to achieve an ultrahigh rate for LIBs.

A facile ionic liquid and p-toluenesulfonic acid pretreatment of herb residues: Enzymatic hydrolysis and lignin valorization

This study aimed to develop a promising biorefinery technology for the value-added utilization of herb residues by using ionic liquid (IL) assisted by aromatic acid (p-toluenesulfonic acid, TsOH) pretreatment. The result showed that the addition of low concentration of TsOH into IL could effectively deconstruct the recalcitrant intercellular structure of herb residues and rapidly extract the lignin fraction. Under the optimum conditions (79% IL, 1.0% TsOH, and 20% H2O at 130 °C and 2 h), the highest cellulose recovery yield of 96.4%, the lignin removal rate of 79.9% and ideal saccharification yield of 98.9% were achieved. Moreover, the main byproduct lignin exhibited comparable yield, high purity, and thermal stability, suggesting the potential application in the conversion of bio-based chemicals and materials. Furthermore, the IL was successfully recycled three times and the recovery rate was at least 95% each time. High saccharification yields and lignin recovery were maintained during all cycles. The hemicellulose-derived saccharides were the main impurities detected in the recycled IL. Overall, this work presents a novel green pretreatment process that can effectively utilize herb residues.

Ionic Liquid Assisted Electrospinning of Porous LiFe0.4 Mn0.6 PO4 /CNFs as Free-Standing Cathodes with a Pseudocapacitive Contribution for High-Performance Lithium-Ion Batteries.

In pursuit of high-performance cathode materials for lithium-ion batteries with high energy and power densities, porous LiFe0.4 Mn0.6 PO4 /CNF free-standing electrodes have been successfully prepared through a facile ionic liquid (IL) assisted electrospinning method. Owing to the hierarchical porosity and N-doped carbon layer derived from the ionic liquid, the resulting electrodes exhibited superior electrochemical performances with an improvement of conductivity and pseudocapacitive contribution, delivering a discharge capability of 162.7, 133.5, 114.5, and 102.6 mAh g-1 at the current rates of 0.1, 1, 5, and 10 C, respectively. It is highly expected that this facile IL-assisted electrospinning method will lead to further developments for other phosphate-based free-standing electrodes, which offers a new route in designing polyanionic cathodes for high-performance Li-ion batteries.

A facile ionic liquid approach to prepare cellulose fiber with good mechanical properties directly from corn stalks

It is very difficult to directly spin the lignocellulose without pretreatment. Ionic liquids (ILs) are promising solvent to dissolve lignocellulose to prepare cellulose fiber. However, the degree of cellulose polymerization（DP）is reduced when lignocellulose is dissolved in ILs, and the lignin removal rate is low. The elongation at break and tensile strength of the fibers obtained by spinning the lignocellulose dissolved in ILs are poor. In this paper, preparing cellulose fiber directly from lignocellulose based on dissolving corn stalk via [C4mim]Cl-L-arginine binary system is achieved. It shows that the removal rate of lignin can reach 92.35% and the purity of cellulose can reach 85.32% after corn stalk was dissolved at 150 °C for 11.5 h when the mass fraction of arginine is 2.5%. The elongation at break of fiber reached 10.12% and the tensile strength reached 420 MPa. It is mainly due to the fact that L-arginine not only inhibits the degradation of cellulose but also promotes the delignination. Without any pulping or pretreatment, preparing cellulose fibers via direct dissolution and extrusion may provide a simple and effective way to prepare many novel cellulose materials.

A facile ionic liquid approach to prepare cellulose-rich aerogels directly from corn stalks

Cellulose-rich aerogels were prepared through a one-step approach whereby lignin was separated from the other components of corn stalks using a coupled solvent system: IL and ASA.

Ionic liquid induced electrostatic self-assemble of reduced graphene oxide for high-performance all-solid-state flexible symmetric supercapacitor

Flexible solid-state supercapacitors are arousing tremendous research enthusiasm in modern wearable and portable electronic equipment. Fabricating flexible electrode materials turns out to be a key challenge. Here, we developed a facile ionic liquid induced electrostatic self-assemble method to prepare bendable reduced graphene oxide (ILG). Due to electrostatic interaction between ionic liquid and graphene oxide, the ionic liquid can effectively prevent the aggregation of GO layers and protect partial O-containing functional groups at the same time. The IL plays great roles of a protector and stabilizer. The obtained ILG shows high specific capacitance (260 F g−1 at 0.5 A g−1), superior rate capability (62% from 0.5 to 100 A g−1) and outstanding energy density (9.03 W h kg−1 at 125 W kg−1) in 6 M KOH electrolyte. The constructed flexible symmetric all-solid-state supercapacitor also exhibits a specific capacitance of 195 F g−1 at 0.5 A g−1 and approximately 100% capacitance retention at different bending angels. The one-step approach might provide us with a new avenue for designing other flexible materials used in bendable devices.

Graphene-like boron nitride induced accelerated charge transfer for boosting the photocatalytic behavior of Bi4O5I2 towards bisphenol a removal

A novel graphene-like BN/Bi4O5I2 2D-2D stacking has been prepared via a facile ionic liquid 1-hexyl-3-methylimidazolium iodide ([Hmim]I) assisted solvothermal method with the proper pH for the first time. Series of characterizations, such as XRD, XPS, FT-IR, TEM, BET, PL, EIS and ESR have been applied to analyze the composition, morphology, structure, optical and electronic properties of the graphene-like BN/Bi4O5I2 composites. The sufficient contact and strong interfacial interaction between the graphene-like BN and Bi4O5I2 nanosheets can be effective constructed. Colorless endocrine disrupter bisphenol A (BPA) was chosen as the target pollutant to evaluate the photocatalytic degradation performance of the pure Bi4O5I2 nanosheets and graphene-like BN/Bi4O5I2 composites under visible light irradiation. The enhanced photocatalytic activity of the graphene-like BN/Bi4O5I2 composites could be attributed to the higher electron transfer ability over the graphene-like BN nanosheet and thus the molecular oxygen can be better activated. Superoxide radical and hole were determined to be the main active species during the photodegradation process. This work will provide a new sight into the design of other two-dimensional atomic level material based composites for photocatalysis.

New Route for the Synthesis of Thiazolidine 2,4dione Azepine Derivatives

A new facile ionic liquid mediated proficient method is developed for the synthesis of structurally new thiazepine and oxazepine derivatives of thiazolidine 2,4‐dione. This protocol proceeds through, one‐pot three component reaction between fused cyclic ketone, substituted aromatic aldehyde, 2‐amino phenol and 2‐amino thiobenzene at room temperature to yield structurally new derivatives.

Ionic liquid-assisted solvothermal synthesis of three-dimensional hierarchical copper sulfide microflowers at a low temperature with enhanced photocatalytic performance

Three-dimensional (3D) hierarchical copper sulfide (CuS) microflowers have been successfully constructed by a facile ionic liquid (1-butyl-3-methylimidazolium chloride, [BMIm]Cl)-assisted solvothermal method at a low temperature (65 °C). Covellite CuS assembled into nanoflakes with a thickness of 8–10 nm and a lateral dimension of about 700 nm was obtained by the decomposition of intermediate complex Cu3(TAA)3Cl3 (thioacetamide, TAA) blocks. The ionic liquid (IL) could serve as a solvent, ligand, and structure-directing agent, which played an important role in the morphologies of Cu3(TAA)3Cl3 and CuS. It is found that CuCl could be interacted with [BMIm]Cl, leading to the formation of [BMIm]CuCl2. Furthermore, the CuS crystal growth along the <001> direction was inhibited by the absorption of alkylimidazolium rings ([BMIm]+) on the (001) facets of CuS. The morphology and size of CuS were controllable by changing the concentration of [BMIm]Cl. Moreover, 3D hierarchical CuS microflowers used as the photocatalyst showed enhanced visible-light photocatalytic activity for the degradation of methylene blue (MB), due to their large specific surface area, mesoporous structure, and advantageous optical properties. This synthetic method could be expanded to prepare other metal chalcogenides, owing to its simple and safe operation, mild reaction conditions, and low cost.

A facile ionic liquid promoted synthesis, cholinesterase inhibitory activity and molecular modeling study of novel highly functionalized spiropyrrolidines.

A series of novel dimethoxyindanone embedded spiropyrrolidines were synthesized in ionic liquid, [bmim]Br and were evaluated for their inhibitory activities towards cholinesterases. Among the spiropyrrolidines, compound 4f exhibited the most potent activity with an IC50 value of 1.57 µM against acethylcholinesterase (AChE). Molecular docking simulation for the most active compound was employed with the aim of disclosing its binding mechanism to the active site of AChE receptor.

Active and Stable Platinum/Ionic Liquid/Carbon Nanotube Electrocatalysts for Oxidation of Methanol

Platinum (Pt) nanoparticles (NPs) on carbon nanotubes (CNTs) from PtCl62– ions through a facile ionic liquid (IL)-assisted method has been developed and used for methanol oxidation. 1-Butyl-3-methylimidazolium (BMIM) with four different counter ions (PF6–, Cl–, Br–, and I–) have been tested for the preparation of Pt/IL/CNT nanohybrids, showing the counter ions of ILs play an important role in the formation of small sizes of Pt NPs. Only [BMIM][PF6] and [BMIM][Cl] allow reproducible preparation of Pt/IL/CNT nanohybrids. The electroactive surface areas of Pt/[BMIM][PF6]/CNT, Pt/[BMIM][Cl]/CNT, Pt/CNT, and commercial Pt/C electrodes are 62.8, 101.5, 78.3, and 87.4 m2 g-1, respectively. The Pt/[BMIM][Cl]/CNT nanohybrid-modified electrodes provide higher catalytic activity (251.0 A g–1) at a negative onset potential of -0.60 V than commercial Pt/C-modified ones do (133.5 A g–1) at -0.46 V. The Pt/[BMIM][Cl]/CNT electrode provides the highest ratio (4.52) of forward/reverse oxidation current peak, revealing a little accumulation of carbonaceous residues.

Active and stable platinum/ionic liquid/carbon nanotube electrocatalysts for oxidation of methanol

Abstract Platinum (Pt) nanoparticles (NPs) on carbon nanotubes (CNTs) have been prepared from PtCl6 2− ions through a facile ionic liquid (IL)-assisted method and used for methanol oxidation. 1-Butyl-3-methylimidazolium (BMIM) with four different counter ions (PF6 −, Cl−, Br−, and I−) has been tested for the preparation of Pt/IL/CNT nanohybrids, showing the counter ions of ILs play an important role in the formation of small sizes of Pt NPs. Only [BMIM][PF6] and [BMIM][Cl] allow reproducible preparation of Pt/IL/CNT nanohybrids. The electroactive surface areas of Pt/[BMIM][PF6]/CNT, Pt/[BMIM][Cl]/CNT, Pt/CNT, and commercial Pt/C electrodes are 62.8, 101.5, 78.3, and 87.4 m2 g−1, respectively. The Pt/[BMIM][Cl]/CNT nanohybrid-modified electrodes provide higher catalytic activity (251.0 A g−1) at a negative onset potential of −0.60 V than commercial Pt/C-modified ones do (133.5 A g−1) at −0.46 V. The Pt/[BMIM][Cl]/CNT electrode provides the highest ratio (4.52) of forward/reverse oxidation current peak, revealing a little accumulation of carbonaceous residues.

Facile Ionic Liquid Combustion Synthesis and Visible-light Photocatalytic Ability of Mesoporous FeAl2O4 with High Specific Surface Area

Abstract A facile synthesis route of pure FeAl2O4 via self-combustion of ionic liquid is developed using (C2H5)2NH·HCl and urea as cofuels. (C2H5)2NH·HCl not only is the source of cation in ionic liquid but also serves as fuel. The products possess pure hercynite phase, mesoporous structure, and large specific surface areas (89–185 m2 g−1). The visible-light photocatalytic activity of FeAl2O4 is also reported for the first time.

Electrochemistry of Zirconium Tetrachloride in the Ionic Liquid N‐Butyl‐N‐methylpyrrolidinium Bis(trifluoromethylsulfonyl)imide: Formation of Zr(III) and Exploitation of ZrCl4 as a Facile Ionic Liquid Drying Agent

AbstractThe electrochemistry of zirconium tetrachloride in the ionic liquid N‐butyl‐N‐methylpyrrolidinium bis(trifluoromethylsulfonyl)imide has been studied, and the one electron reduction is proved by chronoamperometry. Furthermore, we report the application of ZrCl4 as a facile and general ionic liquid drying agent for use in voltammetry.

Facile Ionic Liquid–Mediated Protocol for the Regioselective Synthesis of 1,5-Benzothiazepines

An efficient one-step ionic liquid–mediated green protocol for the regioselective synthesis of (+)/(±)-cis-2-(4-methoxy/benzyloxyphenyl)-3-hydroxy-2,3-dihydro-1,5-benzothiazepin-4-[5H]-ones has been developed from the reaction between substituted 2-aminobenzenethiol and methyl-(±)-trans-3-(4-methoxy/benzyloxy phenyl)glycidate, under nitrogen atmosphere, at 60 ± 2 °C. The reaction has been performed in ionic liquids (viz, 1-butyl-3-methylimidazolium bromide/hexafluorophosphate), and the yields of the 1,5-benzothiazepine derivatives were found to be excellent. The cis-stereoisomer was obtained as the major product along with a trans-isomer as minor product.