Synthesis of Functional Nanomaterials in Ionic Liquids

Ionic Liquids in Metal, Photo-, Electro-, and (Bio) Catalysis

Ionic liquids (ILs) have unique physicochemical properties that make them advantageous for catalysis, such as low vapor pressure, non-flammability, high thermal and chemical stabilities, and the ability to enhance the activity and stability of (bio)catalysts. ILs can improve the efficiency, selectivity, and sustainability of bio(transformations) by acting as activators of enzymes, selectively dissolving substrates and products, and reducing toxicity. They can also be recycled and reused multiple times without losing their effectiveness. ILs based on imidazolium cation are preferred for structural organization aspects, with a semiorganized layer surrounding the catalyst. ILs act as a container, providing a confined space that allows modulation of electronic and geometric effects, miscibility of reactants and products, and residence time of species. ILs can stabilize ionic and radical species and control the catalytic activity of dynamic processes. Supported IL phase (SILP) derivatives and polymeric ILs (PILs) are good options for molecular engineering of greener catalytic processes. The major factors governing metal, photo-, electro-, and biocatalysts in ILs are discussed in detail based on the vast literature available over the past two and a half decades. Catalytic reactions, ranging from hydrogenation and cross-coupling to oxidations, promoted by homogeneous and heterogeneous catalysts in both single and multiphase conditions, are extensively reviewed and discussed considering the knowledge accumulated until now.

Ionic Liquids-Driven Cluster-to-Cluster Conversion of Polyhydrido Copper(I) Clusters Cu7H5 to Cu8H6 and Cu12H9

Although ionic liquids (ILs) are of prime interest for the synthesis of various nanomaterials, they are scarcely utilized for the polyhydrido copper(I) [Cu(I)H] clusters. Herein, two air-stable Cu(I)H clusters, [Cu8H6(dppy)6](NTf2)2 (Cu8H6) and {Cu12H9(dppy)6[N(CN)2]3} (Cu12H9), are synthesized in high yields for the first time from the ILs-driven conversion of an unprecedented cluster [Cu7H5(dppy)6](ClO4)2 (Cu7H5) by a facile three-layers diffusion crystal (TLDC) method, strategically introducing IL-NTf2 and IL-N(CN)2 as two types of unusual interfacial crystallized templates, respectively. Their structures are fully characterized by various spectroscopic methods and X-ray crystallography, which shows that the anion of IL plays an important role as an anion template and an anion ligand in controlling the structural conversion of Cu(I)H clusters. Their photophysical properties are also investigated, and it is found that all reported clusters exhibit red luminescence with λem ranging from 600 to 690 nm.

Trace Ionic Liquid-Assisted Orientational Growth of Cu2 O (110) Facets Promote CO2 Electroreduction to C2 Products

Cu2 O has great advantages for CO2 electroreduction to C2 products, of which the activity and selectivity are closely related to its crystal facets. In this work, density functional theory calculation indicated that the (110) facets of Cu2 O had a lower energy barrier for the C-C coupling compared to the (100) and (111) facets. Therefore, Cu2 O(110) facets were successfully synthesized with the assistance of trace amounts of the ionic liquid 1-butyl-3-methylimidazolium ([Bmim]BF4 ) by a sample wet-chemical method. A high faradaic efficiency of 71.1 % and a large current density of 265.1 mA cm-2 toward C2 H4 and C2 H5 OH were achieved at -1.1 V (vs. reversible hydrogen electrode) in a flow cell. The in situ and electrochemical analysis indicated that it possessed the synergy effects of strong adsorption of *CO2 and *CO, large active area, and excellent conductivity. This study provided a new way to enhance the C2 selectivity of CO2 electroreduction on Cu2 O by crystal structure engineering.

Fractal Design of Hierarchical PtPd with Enhanced Exposed Surface Atoms for Highly Catalytic Activity and Stability

Hierarchical assembly of arc-like fractal nanostructures not only has its unique self-similarity feature for stability enhancement but also possesses the structural advantages of highly exposed surface-active sites for activity enhancement, remaining a great challenge for high-performance metallic nanocatalyst design. Herein, we report a facile strategy to synthesize a novel arc-like hierarchical fractal structure of PtPd bimetallic nanoparticles (h-PtPd) by using pyridinium-type ionic liquids as the structure-directing agent. Growth mechanisms of the arc-like nanostructured PtPd nanoparticles have been fully studied, and precise control of the particle sizes and pore sizes has been achieved. Due to the structural features, such as size control by self-similarity growth of subunits, structural stability by nanofusion of subunits, and increased numbers of exposed active atoms by the curved homoepitaxial growth, h-PtPd displays outstanding electrocatalytic activity toward oxygen reduction reaction and excellent stability during hydrothermal treatment and catalytic process.

Effects of Zwitterions on Structural Anomalies in Ionic Liquid Glasses Studied by EPR

Ionic liquids (ILs) form a variety of nanostructures due to their amphiphilic nature. Recently, unusual structural phenomena have been found in glassy ILs near their glass transition temperatures; however, in all studied cases, IL cations and anions were in the form of separate moieties. In this work, we investigate for the first time such structural anomalies in zwitterionic IL glasses (ZILs), where the cation and anion are bound in a single molecule. Such binding reasonably restricts mutual diffusion of cations and anions, leading to modification of nano-ordering and character of structural anomalies in these glassy nanomaterials, as has been investigated using Electron Paramagnetic Resonance (EPR) spectroscopy. In particular, the occurrence of structural anomalies in ZIL glasses was revealed, and their characteristic temperatures were found to be higher compared to common ILs of a similar structure. Altogether, this work broadens the scope of structural anomalies in ionic liquid glasses and indicates new routes to tune their properties.

Graphene-Based Electrochemical Biosensors for Breast Cancer Detection

Breast cancer (BC) is the most common cancer in women, which is also the second most public cancer worldwide. When detected early, BC can be treated more easily and prevented from spreading beyond the breast. In recent years, various BC biosensor strategies have been studied, including optical, electrical, electrochemical, and mechanical biosensors. In particular, the high sensitivity and short detection time of electrochemical biosensors make them suitable for the recognition of BC biomarkers. Moreover, the sensitivity of the electrochemical biosensor can be increased by incorporating nanomaterials. In this respect, the outstanding mechanical and electrical performances of graphene have led to an increasingly intense study of graphene-based materials for BC electrochemical biosensors. Hence, the present review examines the latest advances in graphene-based electrochemical biosensors for BC biosensing. For each biosensor, the detection limit (LOD), linear range (LR), and diagnosis technique are analyzed. This is followed by a discussion of the prospects and current challenges, along with potential strategies for enhancing the performance of electrochemical biosensors.

Ionic liquid-assisted synthesis of mesoporous polymers and carbon materials: the self-assembly mechanism

Soft-templating synthesis has been widely employed to fabricate ordered mesoporous polymer and carbon materials with effectively tuneable pore sizes. However, the commonly used templating agents, block copolymers, are normally decomposed during the process, thus are barely recyclable; this increases the costs and hampers the scale-up feasibility. Therefore, it becomes imperative to seek promising alternatives; amphiphilic ionic liquids (ILs) are excellent candidates due to their good recyclability. This study explored the templating behaviour of IL templates for preparing mesoporous polymers and carbons. In details, the self-assembly of ternary systems (comprising of IL templates, precursors and solvent) were investigated by a combination of coarse-grained molecular dynamics (CGMD) simulations, density function theory (DFT) calculations and experimental techniques. The results indicate that the morphologies of IL templates are tuneable not only by the adjustment of water content in the mixture but also by the selection of suitable precursors. Material precursors containing increasing numbers of hydroxyl moieties also induce various precursor-template spatial correlations, resulting in different topological structures of nanomaterials. This work presents a fundamental investigation into the mechanisms of templating synthesis with amphiphilic ILs as recyclable templates and gives insight into the effective design of coveted carbon nanomaterials for targeted applications.

An Electrochemical Immunosensor Based on Gold-Graphene Oxide Nanocomposites with Ionic Liquid for Detecting the Breast Cancer CD44 Biomarker

We develop a highly sensitive electrochemical immunosensor for the detection of a cluster of differentiation-44 (CD44) antigen, a breast cancer biomarker. The hybrid nanocomposite consists of graphene oxide, ionic liquid, and gold nanoparticles (GO-IL-AuNPs) immobilized on a glassy carbon electrode. GO favors the immobilization of antibodies because of the availability of oxygen functionalities. However, 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM.BF₄) and AuNPs facilitate electron transfer and increase the effective surface area, which enhances the performance of the immunosensor. Furthermore, UV-visible, fourier transform infrared and Raman spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, voltammetry, and electrochemical impedance spectroscopy characterization techniques have been employed to investigate the structural and chemical properties of the nanomaterials. The quantitative detection of CD44 antigen has been accomplished via differential pulse voltammetry and EIS detection techniques. It has been quantified that the proposed immunosensor offers excellent detection ability in both phosphate-buffered saline (PBS) and serum samples. Under optimum conditions, the linear detection range of the immunosensor for CD44 antigen is 5.0 fg mL^-1 to 50.0 μg mL^-1 and the limit of detection is 2.0 and 1.90 fg mL^-1 as observed via DPV and EIS, respectively, in PBS. Additionally, the immunosensor has high sensitivity and specificity and can be successfully applied for the detection of CD44 antigen in clinical samples.

Organic-Inorganic Hybrid Flower-Shaped Microspheres Applied in Photoelectrochemical Sensing

Organic-inorganic hybrid materials are rarely applied in photoelectrochemical (PEC) sensing because of the serious charge-carrier recombination in organic conjugated polymers. In this work, a series of poly(3,4-ethylenedioxythiophene) (PEDOT)/ZnIn2S4 hybrid flower-shaped microspheres were synthesized using ionic liquids (ILs) as the supporting electrolyte for EDOT electropolymerization and as the regulating reagent for controlling ZnIn2S4 growth, respectively. It was found that the hybrid material [HOEMIM]NTf2-PEDOT/[HOEMIM]BF4-ZnIn2S4 ([HOEMIM]+: 1-hydroxyethyl-3-methylimidazolium cation; NTf2-: bis(trifluoromethanesulfonyl)amide) was the optimal one, with a smooth, transparent, and continuous polymer film covering the uniform and ordered cross-linked nanosheet arrays. The hybrid material could produce a high anodic photocurrent, which was about 78 times as high as that produced by the [HOEMIM]BF4-ZnIn2S4. The enhancement effect should be the highest among all the organic-inorganic hybrid materials reported so far. This was related to its unique micromorphology structure, p-n heterojunction, and the coexisting ILs, which restrained the charge-carrier recombination in PEDOT and enhanced PEDOT sensitization to ZnIn2S4. Then, a carcinoembryonic antigen PEC immunosensor was constructed based on the photoanodic sensing platform, and it exhibited good performance. Furthermore, the [HOEMIM]BF4-ZnIn2S4 was treated with NaClO solution to create the [HOEMIM]NTf2-PEDOT/[HOEMIM]BF4-S-ZnwInxSyOz general platform for both photoanodic and photocathodic sensing. As a proof of concept, L-cysteine and dissolved oxygen were used as models for photoanodic and photocathodic sensing, respectively. The results demonstrated that the general PEC platform was quite competent. This work opens up a window for the design of organic-inorganic hybrid PEC materials and will promote the application of such hybrid materials in PEC biosensing.

Controllable Synthesis of a Loofah-Like Cobalt-Nickel Selenide Network as an Efficient Electrocatalyst for the Hydrogen Evolution Reaction

The rational design and construction of noble metal-free electrocatalysts featuring high efficiency and low cost are important for the hydrogen evolution reaction (HER). A significant development in the synthesis of a loofah-like Co_0.6Ni_0.4Se₂ architecture (expressed as Co_0.6Ni_0.4Se₂-LN) electrocatalyst on carbon cloth through a three-step method is reported. Both the ionic liquid 1-dodecyl-3-methylimidazolium acetate (IL, [C₁₂MIm]Ac) and the molar ratio of Co to Ni play a pivotal role in the synthesis of Co_0.6Ni_0.4Se₂-LN with 3D hierarchical architecture. Co_0.6Ni_0.4Se₂-LN exposes abundant active sites and provides hierarchical and stable transfer channels for both electrolyte ions and electrons, which results in outstanding HER performance. Impressively, Co_0.6Ni_0.4Se₂-LN shows a low overpotential of 163 mV at 10 mA cm^-2, a small Tafel slope of 40 mV dec^-1, and superior stability to continuously catalyze the generation of H₂ for 40 h. This study offers a new perspective to the synthesis of high-efficiency inexpensive electrocatalysts for HER and also presents a good example for investigating the potential application of ILs in the synthesis of functional materials.

Ionothermal Synthesis of Sulfidobismuth spiro-Dicubane Cations

Bi2 S3 was dissolved in the presence of NaCl in the ionic liquid [BMIm]Cl ⋅ 4AlCl3 (BMIm=1-n-butyl-3-methylimidazolium) through annealing the mixture at 180 °C. Upon cooling to room temperature, orange, air-sensitive crystals of Na(Bi7 S8 )[S(AlCl3 )3 ]2 [AlCl4 ]2 (1) precipitated. X-ray diffraction on single-crystals of 1 revealed a triclinic crystal structure that contains (Bi7 S8 )5+ spiro-dicubanes, [S(AlCl3 )3 ]2- tetrahedra triples, isolated [AlCl4 ]- tetrahedra, and sodium cations.

Aqueous, Mixed Micelles as a Means of Delivering the Hydrophobic Ionic Liquid EMIM TFSI to Graphene Oxide Surfaces

Most ionic liquids (ILs) are not surface-active and cannot, alone, be directed to assemble at surfaces─despite their potential as nonvolatile structure-directing agents and use as advanced materials in a multitude of applications. In this work, we investigate aqueous systems of common nonionic surfactants (Triton X-100 and Tween 20), which we use to solubilize 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. The resulting solution of mixed micelle leads to spontaneous adsorption of the IL/surfactant complex onto graphene oxide (GO) surfaces, forming a compact film. Adsorption isotherms generated by fluorescence labeling of the IL and surfactant phases are used to quantify the extent of adsorption. While sensitive to the GO dispersion concentration, upwards of 3 g IL/g GO adsorb under dilute conditions. Atomic force microscopy is used to show that the adsorbed layer uniformly distributes as an ∼1 nm thick coating (per GO side) as the system reaches the first plateau of a Langmuir-type isotherm. Adsorption beyond this plateau is possible but leads to thicker (>30 nm), inhomogeneous adsorbed layers. Both micellar size in solution and adsorbed layer thickness reduce upon the addition of IL to the surfactant phase, suggesting significant interactions among the materials and nonideal mixing of the components.

Functional Ionic Liquids Decorated Carbon Hybrid Nanomaterials for the Electrochemical Biosensors

Ionic liquids are gaining high attention due to their extremely unique physiochemical properties and are being utilized in numerous applications in the field of electrochemistry and bio-nanotechnology. The excellent ionic conductivity and the wide electrochemical window open a new avenue in the construction of electrochemical devices. On the other hand, carbon nanomaterials, such as graphene (GR), graphene oxide (GO), carbon dots (CDs), and carbon nanotubes (CNTs), are highly utilized in electrochemical applications. Since they have a large surface area, high conductivity, stability, and functionality, they are promising in biosensor applications. Nevertheless, the combination of ionic liquids (ILs) and carbon nanomaterials (CNMs) results in the functional ILs-CNMs hybrid nanocomposites with considerably improved surface chemistry and electrochemical properties. Moreover, the high functionality and biocompatibility of ILs favor the high loading of biomolecules on the electrode surface. They extremely enhance the sensitivity of the biosensor that reaches the ability of ultra-low detection limit. This review aims to provide the studies of the synthesis, properties, and bonding of functional ILs-CNMs. Further, their electrochemical sensors and biosensor applications for the detection of numerous analytes are also discussed.

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

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.

Controlled Nanostructuration of Cobalt Oxyhydroxide Electrode Material for Hybrid Supercapacitors

Nanostructuration is one of the most promising strategies to develop performant electrode materials for energy storage devices, such as hybrid supercapacitors. In this work, we studied the influence of precipitation medium and the use of a series of 1-alkyl-3-methylimidazolium bromide ionic liquids for the nanostructuration of β(III) cobalt oxyhydroxides. Then, the effect of the nanostructuration and the impact of the different ionic liquids used during synthesis were investigated in terms of energy storage performances. First, we demonstrated that forward precipitation, in a cobalt-rich medium, leads to smaller particles with higher specific surface areas (SSA) and an enhanced mesoporosity. Introduction of ionic liquids (ILs) in the precipitation medium further strongly increased the specific surface area and the mesoporosity to achieve well-nanostructured materials with a very high SSA of 265 m2/g and porosity of 0.43 cm3/g. Additionally, we showed that ILs used as surfactant and template also functionalize the nanomaterial surface, leading to a beneficial synergy between the highly ionic conductive IL and the cobalt oxyhydroxide, which lowers the resistance charge transfer and improves the specific capacity. The nature of the ionic liquid had an important influence on the final electrochemical properties and the best performances were reached with the ionic liquid containing the longest alkyl chain.

The crystal structure of 1-dodecylpyridin-1-ium bromide monohydrate, C17H32BrNO

C17H32BrNO, triclinic, P 1 ‾ $P\bar{1}$ (no. 2), a = 5.344(3) Å, b = 7.871(5) Å, c = 23.614(15) Å, α = 95.990(12)°, β = 95.747(12)°, γ = 98.386(12)°, V = 970.5(11) Å3, Z = 2, R gt(F) = 0.0550, wR ref(F 2) = 0.1527, T = 293(2) K.

CCDC no.: 1983264

Metal Assisted Synthesis of Cationic Sulfidobismuth Cubanes in Ionic Liquids

Bi2 S3 was dissolved in the presence of either AuCl/PtCl2 or AgCl in the ionic liquids [BMIm]Cl ⋅ xAlCl3 (BMIm=1-n-butyl-3-methylimidazolium; x=4-4.3) through annealing the mixtures at 180 or 200 °C. Upon cooling to room temperature, orange, air-sensitive crystals of [BMIm](Bi4 S4 )[AlCl4 ]5 (1) or Ag(Bi7 S8 )[S(AlCl3 )3 ]2 [AlCl4 ]2 (2) precipitated, respectively. 1 did not form in the absence of AuCl/PtCl2 , suggesting an essential role of the metal cations. X-ray diffraction on single-crystals of 1 revealed a monoclinic crystal structure that contains (Bi4 S4 )4+ heterocubanes and [AlCl4 ]- tetrahedra as well as [BMIm]+ cations. The intercalation of the ionic liquid was confirmed via solid state NMR spectroscopy, revealing unusual coupling behavior. The crystal structure of 2 consists of (Bi7 S8 )5+ spiro-dicubanes, [S(AlCl3 )3 ]2- tetrahedra triples, isolated [AlCl4 ]- tetrahedra, and heavily disordered silver(I) cations. No cation ordering took place in 2 upon slow cooling to 100 K.

Metal Sulfide Nanoparticle Synthesis with Ionic Liquids - State of the Art and Future Perspectives

Metal sulfides are among the most promising materials for a wide variety of technologically relevant applications ranging from energy to environment and beyond. Incidentally, ionic liquids (ILs) have been among the top research subjects for the same applications and also for inorganic materials synthesis. As a result, the exploitation of the peculiar properties of ILs for metal sulfide synthesis could provide attractive new avenues for the generation of new, highly specific metal sulfides for numerous applications. This article therefore describes current developments in metal sulfide nanoparticle synthesis as exemplified by a number of highlight examples. Moreover, the article demonstrates how ILs have been used in metal sulfide synthesis and discusses the benefits of using ILs over more traditional approaches. Finally, the article demonstrates some technological challenges and how ILs could be used to further advance the production and specific property engineering of metal sulfide nanomaterials, again based on a number of selected examples.

Uniform heterostructured MnOx/MnCO3/Fe2O3 nanocomposites assembled in an ionic liquid for highly selective oxidation of 5-hydroxymethylfurfural

Uniform heterostructured MnO_x/MnCO₃/Fe₂O₃ nanocomposites assembled in the ionic liquid 1-butyl-3-methyl-imidazolium chloride ([BMim]Cl) exhibit highly selective oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran.

A new phosphonium-based ionic liquid to synthesize nickel metaphosphate for hydrogen evolution reaction

The electrochemical hydrogen evolution reaction (HER) is a promising strategy for production of hydrogen; however, it is still restricted by appropriate efficient and low-cost electrocatalysts. Herein, for the first time, the n-octylammonium hypophosphite, a kind of protic ionic liquid (IL), was used as a new phosphorus source for the manufacture of nickel metaphosphate (Ni₂P₄O₁₂) electrocatalysts. In contrast to traditional multi-step fabrication processes, the n-octylammonium hypophosphite acted as both reactant and solvent to synthesize Ni₂P₄O₁₂ by a one-step calcination approach. The obtained Ni₂P₄O₁₂ as an alkaline HER catalyst required a low overpotential of 116 mV at -10 mA cm^-2 and a small Tafel slope of 97 mV dec^-1, comparable to the majority of reported Ni-based materials and other phosphate catalysts. Furthermore, this catalyst exhibited robust stability with no distinct attenuation of current density after a long-term durability test in 1 M KOH. Therefore, this task-specific IL strategy with a simple reaction system, reducing the occurrence of side reactions, provided a new perspective on design of high-efficiency metaphosphate electrocatalysts.

A microwave assisted ionic liquid route to prepare bivalent Mn5O8 nanoplates for 5-hydroxymethylfurfural oxidation

In order to develop highly active non-precious metal catalysts for the selective oxidation of the platform compound 5-hydroxymethylfurfural (HMF) to the value-added bio-chemical 2,5-diformylfuran (DFF), we prepared high purity bivalent Mn₅O₈ nanoplates by a microwave-assisted ionic liquid route. The precursor of bivalent Mn₅O₈ nanoplates was formed through π-π stacking between imidazolium rings of the ionic liquid 1-butyl-3-methyl-imidazolium chloride and extending hydrogen bonds between Cl anions and hydrohausmannite. An oriented aggregation growth occurred on the basis of the Ostwald ripening under microwave heating. The high purity bivalent Mn₅O₈ nanoplates obtained through calcination at 550 °C for 2 h exhibited high HMF conversion (51%) and DFF selectivity (94%) at 5 bar of oxygen pressure in 2 h. The high concentration of Mn⁴⁺ on the exterior surfaces of Mn₅O₈ nanoplates as active sites coupled with good crystallinity played key roles for desirable mass and heat transfer, and for fast desorption avoiding over-oxidation. The reaction process over the Mn₅O₈ nanoplates was proposed based on the understanding of Mn⁴⁺ active centers and lattice oxygen via a Mn⁴⁺/Mn²⁺ two-electron cycle to enhance their catalytic performance. Furthermore, the Mn₅O₈ nanoplates could be readily recovered and reused without loss of catalytic activity. Thus, the high purity Mn₅O₈ nanoplates with good catalytic performance raises the prospect of using the type of sole metal oxide for practical applications.

Synthesis of Porous and Highly Crystallinity Vanadium Phosphorus Oxide Catalysts by Multifunctional Biomass-Based Deep Eutectic Solvents

Deep eutectic solvents (DESs) as a novel class of ionic liquid analogues has been widely used in various fields. Herein, a multifunctional biomass-based DES composed of choline chloride (ChCl) and glucose (GLU) was synthesized and used for the modification of vanadium phosphorus oxide (VPO) catalyst, which is the sole catalyst for the selective oxidation of n-butane to maleic anhydride (MA) in industry. The DES is more green, cost-effective and efficient compared with traditional modifier (metal inorganics and organic polymers). A combination of structure and catalytic performance was investigated in detail to deeply understand its functions. Initially, this DES plays the role of structure directing agent at the stage of precursor synthesis, which can induce the formation of active plane and obtain highly crystalline precursors. Accordingly, the active phase with highly crystalline was obtained after the activation of precursors. Additionally, the DES was decomposed during the precursors activation, resulting in the formation of porous structure around 20 nm on the active plane. Besides this, the surface chemical state including the valence state and acid-base property was changed significantly due to the function of DES. All of these lead to about an 11% increase of MA mass yield, which has great significance to the high value utilization of low carbon alkanes.

Design and Synthesis of a Reduced Graphene Oxide/Patronite Composite with Enhanced Lithium-Ion Storage Performance

The construction of graphene-based composites is a novel electrode material design strategy and has become a promising field in new energy material research. However, the rational design principle is still poorly understood, and the synthetic technology urgently needs to be expanded. Here, a novel strategy for the synthesis of a reduced graphene oxide (rGO)/VS₄ nanoparticle (NP) composite is reported using an ionic liquid (IL)-assisted hydrothermal method. The synergistic effects of graphene and IL, which include the π-cation/anion interactions of graphene, the capping agent effect of IL, and their π-π stacking interaction, are responsible for the synthesis of the composite, achieving delicate tailoring of VS₄ NPs as well as their homogeneous dispersal on the surface of rGO nanosheets. The superior nanostructure of the composite results in enhanced lithium-ion storage performance, such as improved cyclic stability (1009 mA h g^-1 at 0.1 A g^-1 after 150 cycles and 788 mA h g^-1 after 240 cycles even at 1 A g^-1) and rate capability (1540 and 621 mA h g^-1 at 0.1 and 2 A g^-1, respectively). This strategy provides an effective new approach for designing graphene composites and is expected to be applicable in the design of other rGO/transition-metal sulfide composites for energy storage.

An aqueous synthesis of porous PtPd nanoparticles with reversed bimetallic structures for highly efficient hydrogen generation from ammonia borane hydrolysis

Fine construction of porous bimetallic nanomaterials with tunable components and structures is of great importance for their catalytic performance and durability. Herein, we present a facile and mild one-pot route for the preparation of porous PtPd bimetallic nanoparticles (NPs) with reversed structures in aqueous solution for the first time. To this end, a common ionic liquid (IL) 1-hexadecyl-3-methylimidazolium chloride ([C16mim]Cl) is utilized to direct the growth and assembly of porous structures of PtPd NPs. It is shown that the as-prepared porous Pt25Pd75 NPs have obvious hierarchical structures with nanoflowers as subunits and nanorods as basic units. The elemental components and structures of the porous PtPd NPs can be tuned by the precursor ratio and the [C16mim]Cl concentration. Furthermore, various porous PtPd bimetallic structures from Pd-on-Pt to Pt-on-Pd may be efficiently switched by controlling the concentration of glycine. Owing to their high specific surface area, porous hierarchical structures (including mesopores and micropores), and probable electronic effects between Pt and Pd, the porous Pt25Pd75 NPs (Pd-on-Pt structure) are found to exhibit prominent catalytic activity and high stability for hydrogen production from hydrolysis of ammonia borane.

Ionic Liquid-Modulated Synthesis of Porous Worm-Like Gold with Strong SERS Response and Superior Catalytic Activities

Porous gold with well-defined shape and size have aroused extensive research enthusiasm due to their prominent properties in various applications. However, it is still a great challenge to explore a simple, green, and low-cost route to fabricate porous gold with a “clean” surface. In this work, porous worm-like Au has been easily synthesized in a one-step procedure from aqueous solution at room temperature under the action of ionic liquid tetrapropylammonium glycine ([N₃₃₃₃][Gly]). It is shown that the as-prepared porous worm-like Au has the length from 0.3 to 0.6 μm and the width of approximately 100–150 nm, and it is composed of lots of small nanoparticles about 6–12 nm in diameter. With rhodamine 6G (R6G) as a probe molecule, porous worm-like Au displays remarkable surface enhanced Raman scattering (SERS) sensitivity (detection limit is lower than 10⁻¹³ M), and extremely high reproducibility (average relative standard deviations is less than 2%). At the same time, owing to significantly high specific surface area, various pore sizes and plenty of crystal defects, porous worm-like Au also exhibits excellent catalytic performance in the reduction of nitroaromatics, such as p-nitrophenol and p-nitroaniline, which can be completely converted within only 100 s and 150 s, respectively. It is expected that the as-prepared porous worm-like Au with porous and self-supported structures will also present the encouraging advances in electrocatalysis, sensing, and many others.

Integration of mesopores and crystal defects in metal-organic frameworks via templated electrosynthesis

Incorporation of mesopores and active sites into metal-organic framework (MOF) materials to uncover new efficient catalysts is a highly desirable but challenging task. We report the first example of a mesoporous MOF obtained by templated electrosynthesis using an ionic liquid as both electrolyte and template. The mesoporous Cu(II)-MOF MFM-100 has been synthesised in 100 seconds at room temperature, and this material incorporates crystal defects with uncoupled Cu(II) centres as evidenced by confocal fluorescence microscopy and electron paramagnetic resonance spectroscopy. MFM-100 prepared in this way shows exceptional catalytic activity for the aerobic oxidation of alcohols to produce aldehydes in near quantitative yield and selectivity under mild conditions, as well as having excellent stability and reusability over repeated cycles. The catalyst-substrate binding interactions have been probed by inelastic neutron scattering. This study offers a simple strategy to create mesopores and active sites simultaneously via electrochemical formation of crystal defects to promote efficient catalysis using MOFs.

Incorporating mesopores and active sites into metal-organic framework materials has proven advantageous for their catalytic application, but remains challenging to achieve. Here the authors obtain mesoporous, defect-rich metal-organic frameworks through templated electrosynthesis using ionic liquids as both electrolyte and template.

Ionic liquids to monitor the nano-structuration and the surface functionalization of material electrodes: a proof of concept applied to cobalt oxyhydroxide

This paper reports on an innovative and efficient approach based on the use of ionic liquids to govern the nano-structuration of HCoO₂, in order to optimize the porosity and enhance the ionic diffusion through the electrode materials. In this work, we show that (1-pentyl-3-methyl-imidazolium bromide (PMIMBr) and 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF₄)) ionic liquids (ILs) used as templates during the synthesis orientate the nanoparticle aggregation which leads to increase of the porosity and the average pore size of the electrode material. It is also demonstrated that the ILs are strongly bonded to the HCoO₂ surface, leading to surface functionalized HCoO₂ materials, also called nanohybrids. This surface tailoring stabilizes the material upon cycling and shifts the oxidation potential linked to the Co(iii)/Co(iv) redox couple to lower voltage in an alkaline 5 M KOH electrolyte. The surface and porosity optimizations facilitate the ionic diffusion through the material, improve the electron transfer ability within the electrode and lead to greatly enhanced specific capacity in both alkaline 5 M-KOH and neutral 0.5 M-K₂SO₄ aqueous electrolytes (66.7 mA h g^-1 and 47.5 mA h g^-1 respectively for HCoO₂-PMIMBr and HCoO₂-EMIMBF₄ compared to 18.1 mA h g^-1 for bare HCoO₂ in 5 M-KOH at 1 A g^-1).

Specifically Designed Ionic Liquids—Formulations, Physicochemical Properties, and Electrochemical Double Layer Storage Behavior

Two key features—non-volatility and non-flammability—make ionic liquids (ILs) very attractive for use as electrolyte solvents in advanced energy storage systems, such as supercapacitors and Li-ion batteries. Since most ILs possess high viscosity and are less prone to dissolving common electrolytic salts when compared to traditional electrolytic solvents, they must be formulated with low viscosity thinner solvents to achieve desired ionic conductivity and dissolution of electrolyte salts in excess of 0.5 M concentration. In the past few years, our research group has synthesized several specifically designed ILs (mono-cationic, di-cationic, and zwitterionic) with bis(trifluoromethylsulfonyl)imide (TFSI) and dicyanamide (DCA) as counter anions. This article describes several electrolyte formulations to achieve superior electrolytic properties. The performance of a few representative IL-based electrolytes in supercapacitor coin cells is presented.

Mechanistic insight into the self-coupling of 5-hydroxymethyl furfural to C12 fuel intermediate catalyzed by ionic liquids

DFT calculations have been carried out to obtain insight into the self-coupling of biomass-based 5-hydroxymethyl furfural (HMF) to C₁₂ fuel intermediate 5,5′-dihydroxymethyl furoin (DHMF) catalyzed by ionic liquids (ILs). It was found that acetate-based IL or thiazolium IL in combination with the additive Et₃N show high catalytic performance, wherein N-heterocyclic carbons (NHCs) derived from the cations of ILs act as the nucleophiles and the protonated acetate anion or the [Et₃NH]⁺ acts as the proton shuttle. The effectiveness of this catalysis is attributed to the proton-shared three-center-four-electron (3c-4e) bonds between HMF and HOAc or [Et₃NH]⁺, which stabilize the transition states and the intermediates. In addition, the results of the calculations also confirm that the nucleophilicity and basicity of NHCs are key factors for the self-coupling reaction. These results rationalize the experimental findings and offer valuable insights into understanding the catalysis of ILs.

The self-coupling of HMF to DHMF catalyzed by ionic liquids has been rationalized well by performing DFT calculations.

Green chemical engineering in China

In China, the rapid development greatly promotes the national economic power and living standard but also inevitably brings a series of environmental problems. In order to resolve these problems fundamentally, Chinese scientists have been undertaking research in the area of green chemical engineering (GCE) for many years and achieved great progresses. In this paper, we reviewed the research progresses related to GCE in China and screened four typical topics related to the Chinese resources characteristics and environmental requirements, i.e. ionic liquids and their applications, biomass utilization and bio-based materials/products, green solvent-mediated extraction technologies, and cold plasmas for coal conversion. Afterwards, the perspectives and development tendencies of GCE were proposed, and the challenges which will be faced while developing available industrial technologies in China were mentioned.

Modulating Chirality-Selective Photoluminescence of Single-Walled Carbon Nanotubes by Ionic Liquids

The chirality-selective near-infrared emission of surfactant-stabilized single-wall carbon nanotubes could be controlled by simply varying the anion of the commonly used 1-butyl-3-methylimidazolium ionic liquids. This result advances the notion of the designer solvent ability of ionic liquids and provides opportunities for modulating the properties of nanomaterials.

Monitoring the solvation process and stability of Eu2+ in an ionic liquid by in situ luminescence analysis

Ionic liquids (ILs) offer the remarkable possibility of the direct synthesis of Eu2+-doped nanophosphors in solution, under atmospheric conditions, without the necessity of a high-temperature post-synthetic reduction from its trivalent oxidation state. This work uses for the first time in situ luminescence measurements for monitoring the solvation process of Eu2+ from the solid salt to the IL and its stability against oxidation under atmospheric conditions. Upon the addition of EuBr2 to 1-butyl-3-methyl-imidazolium tetrafluoroborate, the formation of the solvation shell is detected by the shift of the emission band at approximately 24 100 cm−1 assigned to the 5d→4f electronic transitions of Eu2+ within EuBr2 to approximately 22 000 cm−1, assigned to Eu2+ within BminBF4, tracking the time-dependent influence of the Eu2+ coordination environment on the crystal field splitting of its d orbitals. Even though the solubility of EuBr2 was demonstrated to be improved by reducing the concentration and increasing the temperature to 60°C, the performance of reactions at room temperature is recommended for future synthesis of Eu2+ materials in ILs due to the slight oxidation to Eu3+ observed upon heating.

The influence of ionothermal synthesis using BmimBF4 as a solvent on nanophosphor BaFBr:Eu2+ photoluminescence

Ionothermal synthesis is a strongly growing research area due to the outstanding physical and chemical properties of ionic liquids (ILs) in the design of new materials, however, the interaction of these IL molecules with optical materials and their effect on the luminescence properties of the materials are poorly known. In this work, it is shown that the imidazolium based BmimBF4 ionic liquid, used as a solvent during the synthesis, tethers at the surface of the nanoparticles and influences the photoluminescence of the nanophosphor BaFBr:Eu2+ materials. In time resolved spectra, two different emissions are observed for the material synthesized by the ionothermal approach, one corresponding to Eu(ii) 5d-4f transitions in the BaFBr host with a decay time of 843 ns and the other with a much faster decay time compared to the ionic liquid BmimBF4.