Ionic Liquid Precursor Research Articles

One-step assembly of N-doped partially graphitic mesoporous carbon for nitrobenzene reduction

N-doped mesoporous carbon material has been synthesized by a novel one-step assembling strategy using ionic liquid (IL) as the carbon source and structure-directing agent. The obtained mesoporous carbon material has bimodal mesopores (about 3.8 and 9.0nm) and partially graphitic structure with a BET surface area of 372m2/g and mesopore volume of 0.61cm3/g. The nitrogen in the IL precursor can be incorporated into the framework of mesoporous carbon with a content of 3.2wt%. The obtained carbon material shows excellent catalytic performance for nitrobenzene (NB) reduction reaction with an 88.6% yield to aniline (AN).

Bimetallic Ru–Cu Nanoparticles Synthesized in Ionic Liquids: Kinetically Controlled Size and Structure

We report a new synthesis of size-controlled bimetallic Ru–Cu nanoparticles (NPs) in ionic liquids using two organometallic precursors. Interestingly enough, upon mixing ruthenium and copper precursors, smaller bimetallic NPs (1.9–2.8 nm) are formed as compared to single metals (Cu: 5 nm; Ru: 4 nm) in a large range of copper molar fractions (χCu = 0.005–0.91). Surface and microscopy techniques evidence that NPs have metallic copper on the surface and crystalline hexagonal close-packed metallic ruthenium core. This structure is further assessed by the catalytic activity of the bimetallic NPs, showing that conversion of benzene in cyclohexane is reduced with increasing χCu. A new and versatile synthesis of size-controlled bimetallic NPs under 10 nm using different decomposition rates of organometallic precursors in ionic liquids is described.

Crystal‐Facet Engineering of Ferric Giniite by Using Ionic‐Liquid Precursors and Their Enhanced Photocatalytic Performances under Visible‐Light Irradiation

In the work presented here, well-dispersed ferric giniite microcrystals with controlled sizes and shapes are solvothermally synthesized from ionic-liquid precursors by using 1-n-butyl-3-methylimidazolium dihydrogenphosphate ([Bmim][H2PO4]) as phosphate source. The success of this synthesis relies on the concentration and composition of the ionic-liquid precursors. By adjusting the molar ratios of Fe(NO3)3·9H2O to [Bmim][H2PO4] as well as the composition of ionic-liquid precursors, we obtained uniform microstructures such as bipyramids exposing {111} facets, plates exposing {001} facets, hollow spheres, tetragonal hexadecahedron exposing {441} and {111} facets, and truncated bipyamids with carved {001} facets. The crystalline structure of the ferric giniite microcrystals is disclosed by various characterization techniques. It was revealed that [Bmim][H2PO4] played an important role in stabilizing the {111} facets of ferric giniite crystals, leading to the different morphologies in the presence of ionic-liquid precursors with different compositions. Furthermore, since these ferric giniite crystals were characterized by different facets, they could serve as model Fenton-like catalysts to uncover the correlation between the surface and the catalytic performance for the photodegradation of organic dyes under visible-light irradiation. Our measurements indicate that the photocatalytic activity of as-prepared Fenton-like catalysts is highly dependent on the exposed facets, and the surface area has essentially no obvious effect on the photocatalytic degradation of organic dyes in the present study. It is highly expected that these findings are useful in understanding the photocatalytic activity of Fenton-like catalysts with different morphologies, and suggest a promising new strategy for crystal-facet engineering of photocatalysts for wastewater treatment based on heterogeneous Fenton-like process.

Syhthesis of Ionic Liquids: Tips to Produce Highly Pure Ionic Liquids and Obtain Good Yield

Ionic liquids and their precursors in variation of cations side chains which are alkane, ether, disiloxane and trisiloxane have been successfully synthesized including 12 of them are novel compounds. They have been successfully characterized with HNMR, Si-NMR, C-NMR, mass spectrometry, elemental analysis and FT-IR spectroscopy. The synthesis of ionic liquids is carried out by alkylation reaction and metathesis reaction. Even though these methods are conventional and straight forward, they were sometimes more difficult to carry out than reported. In addition, a common problem is that yields of the ionic liquid precursors may be very different from those reported in the literature. Therefore, this paper will comprehensively discuss techniques for the synthesis of ionic liquids precursors and ionic liquids in good yield and high purity.

In(OH)3particles from an ionic liquid precursor and their conversion to porous In2O3particles for enhanced gas sensing properties

The ionic liquid precursor tetrabutylammonium hydroxide (TBAH) is used to synthesize In(OH)3 particles. The ionic liquid TBAH is demonstrated to be effective for the synthesis of In(OH)3 nanorods with a controlled size. The effect of the indium salt and the added water amount on the final products is investigated. The synthesized In(OH)3 nanorods could be further transformed into porous In2O3 rod particles. Specifically, the gas sensing properties of the synthesized porous In2O3 rod particles to various organic compounds (methanol, ethanol, isopropanol, butanol, ethyl acetate and toluene) exhibit remarkable sensitivities, low detection limits and fast response–recovery times, which are superior to the reported In2O3 based sensors. The as-prepared porous In2O3 rod-based sensors thus demonstrate their potential applications in detecting chemical contaminants and dangerous gases.

Phase-transfer hydroxylation of benzene with H2O2 catalyzed by a nitrile-functionalized pyridinium phosphovanadomolybdate

A new nitrile-tethered pyridinium polyoxometalate (POM) was prepared by anion-exchange of the ionic liquid precursor [N-butyronitrile pyridine]Cl ([C3CNpy]Cl) with the Keggin phosphovanadomolybdic acid H5PMo10V2O40 (PMoV2), and the obtained organic POM salt [C3CNpy]4HPMoV2 was characterized by XRD, SEM, TG, 1H NMR, 13C NMR, ESI-MS, CHN elemental analysis, nitrogen sorption experiment, and melting point measure. When used as a catalyst, [C3CNpy]4HPMoV2 causes the first example of reaction-controlled phase-transfer hydroxylation of benzene with H2O2, showing high activity and stable reusability. Based on spectral characterizations and comparisons of reaction results, plus the reversible color change between fresh and recovered catalyst, a unique reaction mechanism is proposed for understanding the highly efficient [C3CNpy]4HPMoV2-catalyzed phase-transfer catalysis. The formation of dissolvable active species [VO(O2)]+ is responsible for the phase-transfer behavior, while the intramolecular charge transfer and the protonated nitrile in cations accelerate the reaction and favor a better catalyst recovery rate.

Synthesis of bimetallic nanoparticles in ionic liquids: Chemical routes vs physical vapor deposition

To meet the constant challenges of miniaturization in the microelectronics industry, new innovative pathways must be explored to produce nano-objects. Ionic liquids (ILs) can be used to generate and stabilize metallic nanoparticles (MNPs) by several physical and chemical routes. Here, the simultaneous decomposition of Ru and Cu organometallic precursors in IL is shown to yield core-shell Ru@CuNPs with smaller diameters and narrower size distributions than the corresponding monometallic NPs, in a broad range of Ru:Cu compositions. They are probably formed by rapid nucleation of Ru cores followed by decomposition of the Cu precursor on their surface. This effect forces the formation of a bimetallic structure that does not form with the use of purely physical processes such as PVD. These Cu, Ru, and Ru@CuNPs could be used for the formation of seed and barrier layers for the metallization of advanced interconnect structures.

Efficient CO2 Capture by Porous, Nitrogen‐Doped Carbonaceous Adsorbents Derived from Task‐Specific Ionic Liquids

The search for a better carbon dioxide (CO(2) ) capture material is attracting significant attention because of an increase in anthropogenic emissions. Porous materials are considered to be among the most promising candidates. A series of porous, nitrogen-doped carbons for CO(2) capture have been developed by using high-yield carbonization reactions from task-specific ionic liquid (TSIL) precursors. Owing to strong interactions between the CO(2) molecules and nitrogen-containing basic sites within the carbon framework, the porous nitrogen-doped compound derived from the carbonization of a TSIL at 500 °C, CN500, exhibits an exceptional CO(2) absorption capacity of 193 mg of CO(2) per g sorbent (4.39 mmol g(-1) at 0 °C and 1 bar), which demonstrates a significantly higher capacity than previously reported adsorbents. The application of TSILs as precursors for porous materials provides a new avenue for the development of improved materials for carbon capture.

Schiff Base Structured Acid–Base Cooperative Dual Sites in an Ionic Solid Catalyst Lead to Efficient Heterogeneous Knoevenagel Condensations

An acid-base bifunctional ionic solid catalyst [PySaIm](3)PW was synthesized by the anion exchange of the ionic-liquid (IL) precursor 1-(2-salicylaldimine)pyridinium bromide ([PySaIm]Br) with the Keggin-structured sodium phosphotungstate (Na(3) PW). The catalyst was characterized by FTIR, UV/Vis, XRD, SEM, Brunauer-Emmett-Teller (BET) theory, thermogravimetric analysis, (1)H NMR spectroscopy, ESI-MS, elemental analysis, and melting points. Together with various counterparts, [PySaIm](3)PW was evaluated in Knoevenagel condensation under solvent and solvent-free conditions. The Schiff base structure attached to the IL cation of [PySaIm](3)PW involves acidic salicyl hydroxyl and basic imine, and provides a controlled nearby position for the acid-base dual sites. The high melting and insoluble properties of [PySaIm](3)PW are relative to the large volume and high valence of PW anions, as well as the intermolecular hydrogen-bonding networks among inorganic anions and IL cations. The ionic solid catalyst [PySaIm](3)PW leads to heterogeneous Knoevenagel condensations. In solvent-free condensation of benzaldehyde with ethyl cyanoacetate, it exhibits a conversion of 95.8 % and a selectivity of 100 %; the conversion is even much higher than that (78.2 %) with ethanol as a solvent. The solid catalyst has a convenient recoverability with only a slight decrease in conversion following subsequent recyclings. Furthermore, the new catalyst is highly applicable to many substrates of aromatic aldehydes with activated methylene compounds. On the basis of the characterization and reaction results, a unique acid-base cooperative mechanism within a Schiff base structure is proposed and discussed, which thoroughly explains not only the highly efficient catalytic performance of [PySaIm](3)PW, but also the lower activities of various control catalysts.

Catalytic performance of montmorillonite clay ion-exchanged with ionic liquids in the cycloaddition of carbon dioxide to allyl glycidyl ether

In this study, various ionic liquids immobilized onto montmorillonite clay (IL-MMT) were prepared by ion-exchange reaction between the ionic liquids and ions in the clay interlayer. Tetra-alkyl ammonium chlorides were used as the ionic liquid precursors. The IL-MMTs were characterized by elemental analyses (EA), BET, XRD, 13C NMR, FT-IR, and SEM. The surface areas and d-spacings of the IL-MMTs increased with increasing alkyl chain lengths. The IL-MMTs showed good catalytic activity for the synthesis of the cyclic carbonate from alkyl glycidyl ether (AGE) and carbon dioxide. The effects of the IL cation structure, and reaction parameters such as temperature and CO2 pressure on the reactivity of IL-MMTs were also discussed. The catalyst could be reused in up to four consecutive runs without a significant reduction in the initial activity.

Heterogeneous Selective Oxidation of Sulfides with H2O2 Catalyzed by Ionic Liquid-Based Polyoxometalate Salts

A group of ionic liquid (IL)-based polyoxometalate (POM) salts were prepared via anion-exchange of imidazolium IL precursors tethered by different carbon chain alkyls with various Keggin POMs. The ...

Ionic liquid precursor-based synthesis of CuO nanoplates for gas sensing and amperometric sensing applications

An ionic liquid precursor benzyltrimethylammonium hydroxide (BTMAH) is explored to synthesize CuO particles. The ionic liquid BTMAH is demonstrated to be effective for synthesis of CuO nanoplates with controlled size. The effect of the copper salt and BTMAH concentration on the final products is investigated. Specifically, the gas-sensing properties of the synthesized CuO nanoplate particles to various organic compounds (ethanol, methanol, ethyl acetate, toluene) exhibit superior sensitivities, and fast response/recovery times. Furthermore, the cyclic voltammetry (CV) of the as-prepared CuO nanoplate particles reveal good electroactivity for the oxidation/reduction of H2O2, which results in an effective amperometric H2O2 sensor.

Electrochemical Deposition of Germanium Sulfide from Room-Temperature Ionic Liquids and Subsequent Ag Doping in an Aqueous Solution

A facile room-temperature electrochemical deposition process for germanium sulfide (GeS(x)) has been developed with the use of an ionic liquid as an electrolyte. The electrodeposition mechanism follows the induced codeposition of Ge and S precursors in ionic liquids generating GeS(x) films. The electrodeposited GeS(x) films were characterized by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) and Raman and X-ray photoelectron spectroscopy (XPS). An aqueous-based Ag doping method was used to dope electrochemically grown GeS(x) films with controlled doping compared to the conventional process, which can be used in next-generation solid-state memory devices.

CuO Nanoparticles from the Strongly Hydrated Ionic Liquid Precursor (ILP) Tetrabutylammonium Hydroxide: Evaluation of the Ethanol Sensing Activity

The sensing potential of CuO nanoparticles synthesized via precipitation from a water/ionic liquid precursor (ILP) mixture was investigated. The particles have a moderate surface area of 66 m(2)/g after synthesis, which decreases upon thermal treatment to below 5 m(2)/g. Transmission electron microscopy confirms crystal growth upon annealing, likely due to sintering effects. The as-synthesized particles can be used for ethanol sensing. The respective sensors show fast response and recovery times of below 10 s and responses greater than 2.3 at 100 ppm of ethanol at 200 °C, which is higher than any CuO-based ethanol sensor described so far.

Phosphate protected fluoride nano-phosphors

A fast and easy 2-in-1 step microwave reaction procedure to phosphate coated nanofluorides allows for the formation of phosphate protected fluoride nanoparticles from simple lanthanide precursors in ionic liquids. The phosphate shell efficiently prevents the fluoride particle from decomposition in an atmosphere (containing oxygen and water) at elevated temperatures.

Thermolytic synthesis of graphitic boron carbon nitride from an ionic liquid precursor: mechanism, structure analysis and electronic properties

Recent work has shown the potential of ionic liquids (ILs) as a precursor for porous networks and nitrogen doped carbon materials. The combination of liquid state and negligible vapour pressure represents almost ideal precursor properties and simplifies the processing drastically. Here, we extend this work to get a deeper insight into the solid formation mechanism and to synthesize a mixed boron carbon nitride species by the thermolysis of N,N′-ethylmethylimidazolium tetracyanoborate (EMIM-TCB), a well-known boron- and nitrogen-containing IL. In contrast to other molecule pyrolysis routes boron carbon nitride shows the average composition “BC3N” and like other IL-derived materials turns out to be distorted graphitic, but thermally and chemically very stable, and possesses favourable electrical properties. The detailed mechanistic investigation using TG-IR, FT-IR, solid-state NMR, Raman, WAXS, EELS, XPS and HRTEM also contributes to the general understanding of IL-based material formation mechanisms.

Synthesis of mesoporous carbon/iron carbide hybrids with unusually high surface areas from the ionic liquid precursor [Bmim][FeCl4

Mesoporous carbon/iron carbide hybrid materials with surface areas reaching 800 m2 g−1 were synthesized via an exotemplating route using monolithic mesoporous silica as template and the ionic liquid 1-butyl-3-methylimidazolium tetrachloridoferrate(III) [Bmim][FeCl4] as carbon and iron source. After heat treatment (750 °C under argon) of the [Bmim][FeCl4] precursor confined within the silica matrix, the silica exotemplate was removed with HF leaving the mesoporous C/Fe3C hybrid behind. The surface areas and the pore sizes depend on the exotemplate and the surface areas a significantly larger than any other surface area reported for C/Fe3C hybrid materials so far. The approach is thus a prototype for the synthesis of high-surface area iron carbide-based hybrid materials with potential application in catalysis.

Synthesis and gas-sensing properties of ZnO particles from an ionic liquid precursor

The synthesis and gas-sensing properties of ZnO particles from an ionic liquid precursor benzyltrimethylammonium hydroxide (BTMAH) is studied. The BTMAH, acting as reactant precursor and solvent, is demonstrated to be effective for synthesis of ZnO particles with controlled morphologies. The effect of the water and zinc salt concentration on the morphology of the synthesized particles is investigated. The gas-sensing tests shows that the sensors based on the synthesized ZnO nanoplates exhibit excellent ethanol-sensing properties.

Highly Stable Noble‐Metal Nanoparticles in Tetraalkylphosphonium Ionic Liquids for in situ Catalysis

Gold and palladium nanoparticles were prepared by lithium borohydride reduction of the metal salt precursors in tetraalkylphosphonium halide ionic liquids in the absence of any organic solvents or external nanoparticle stabilizers. These colloidal suspensions remained stable and showed no nanoparticle agglomeration over many months. A combination of electrostatic interactions between the coordinatively unsaturated metal nanoparticle surface and the ionic-liquid anions, bolstered by steric protection offered by the bulky alkylated phosphonium cations, is likely to be the reason behind such stabilization. The halide anion strongly absorbs to the nanoparticle surface, leading to exceptional nanoparticle stability in halide ionic liquids; other tetraalkylphosphonium ionic liquids with non-coordinating anions, such as tosylate and hexafluorophosphate, show considerably lower affinities towards the stabilization of nanoparticles. Palladium nanoparticles stabilized in the tetraalkylphosphonium halide ionic liquid were stable, efficient, and recyclable catalysts for a variety of hydrogenation reactions at ambient pressures with sustained activity. Aerial oxidation of the metal nanoparticles occurred over time and was readily reversed by re-reduction of oxidized metal salts.

Thermal, Rheological, and Ion-Transport Properties of Phosphonium-Based Ionic Liquids

Phosphonium-based ionic liquids with varying counteranions from commercially available ionic liquid precursors enabled tunable viscosity, ionic conductivity, and thermal stability. Thermogravimetric analysis revealed a relationship between thermal stability and anion composition where anions with lower basicity remained stable to higher temperatures. Determination of glass transition temperatures and melting temperatures using differential scanning calorimetry revealed supercooling, crystallization, and dependence on anion composition. Rheological and ionic conductivity measurements determined the temperature-dependence of the viscosity and ionic conductivity of the phosphonium-based ionic liquids. Arrhenius analyses of conductivity and viscosity provided activation energies, which showed a decrease toward larger, more delocalized anions. An assessment according to the Walden plot displayed their efficacy relative to other ionic liquids.