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To gain a deeper understanding of the TiCl4 solvation effects in multi-component ionic liquids, we performed ab initio molecular dynamics simulations of 1-butyl-3-methylimidazolium [C4C1Im]+, tetrafluoroborate [BF4]-, chloride [Cl]- both with and without water and titanium tetrachloride TiCl4. Complex interactions between cations and anions are observed in all investigated systems. By further addition of water and TiCl4 this complex interaction network is extended. Observations of the radial distribution functions and number integrals show that water and TiCl4 not only compete with each other to interact mainly with [Cl]-, which strongly influences the cation-[BF4]- interaction, but also interact with each other, which leads to the fact that in certain systems the cation-anion interaction is enhanced. Further investigations of the Voronoi polyhedra analysis have demonstrated that water has a greater impact on the nanosegregated system than TiCl4 which is also due to the fact of the shear amount of water relative to all other components and its higher mobility compared to TiCl4. Overall, the polar network of the IL mixture collapses by including water and TiCl4. In the case of [Cl]- chloride enters the water continuum, while [BF4]- remains largely unaffected, which deeply affects the interaction of the ionic liquid (IL) network.

The direct synthesis of crystalline titania nanorods by sol-gel chemistry in a special ionic liquid is reported. Unexpectedly, the high-temperature modification, rutile, is obtained directly under ambient conditions. X-ray diffraction and high-resolution transmission electron microscopy measurements support the highly crystalline and structural quality of the sample. The phase-directing property of the ionic liquids is attributable to the imide group in the counter ion, which exhibits strong interaction with specific rutile faces. Lithium insertion experiments were performed and revealed high and reversible loading capacities of up to 200 mAh g(-1).

The influence of the cation of imidazolium‐derived ionic liquids (ILs) on a low‐temperature solution‐based synthesis of hexagonal tungsten bronze (HTB) type Ti(OH)OF ⋅ 0.66 H2O and bronze‐type TiO2(B) is investigated. The IL (Cxmim BF4) acts as solvent and also as reaction partner with respect to the decomposition of [BF4]−, releasing F−. In the present study, the chain length of the alkyl chain side groups attached to the imidazolium ring was varied (C2mim BF4 to C10mim BF4), and the obtained solids were analyzed by Powder X‐Ray diffraction (PXRD) followed by Rietveld refinement. As a main finding these analyses indicate a transformation of Ti(OH)OF ⋅ 0.66 H2O into TiO2(B), and upon prolonged reaction time finally also into anatase TiO2. Rietveld analysis suggests that when using ILs with longer alkyl chains, the conversion of Ti(OH)OF ⋅ 0.66 H2O is slower compared to syntheses performed with smaller alkyl chains. Hence, Ti(OH)OF ⋅ 0.66 H2O appears to be metastable and is stabilized by long‐chain ILs serving as surfactant attached to the crystallites' surface. In this view, the ILs shield the nanoparticles and thus slow down the conversion into the more stable compounds. This confirms previous findings that ILs act as both, solvent and reaction medium in this reaction, thus enabling the synthesis of peculiar Ti‐oxides. [ABSTRACT FROM AUTHOR]

Decomposition of transition-metal amidinates [M{MeC(N iPr)2} n] [M(AMD) n; M=MnII, FeII, CoII, NiII, n=2; CuI, n=1) induced by microwave heating in the ionic liquids (ILs) 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]), 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][PF6]), 1-butyl-3-methylimidazolium trifluoromethanesulfonate (triflate) ([BMIm][TfO]), and 1-butyl-3-methylimidazolium tosylate ([BMIm][Tos]) or in propylene carbonate (PC) gives transition-metal nanoparticles (M-NPs) in non-fluorous media (e.g. [BMIm][Tos] and PC) or metal fluoride nanoparticles (MF2-NPs) for M=Mn, Fe, and Co in [BMIm][BF4]. FeF2-NPs can be prepared upon Fe(AMD)2 decomposition in [BMIm][BF4], [BMIm][PF6], and [BMIm][TfO]. The nanoparticles are stable in the absence of capping ligands (surfactants) for more than 6 weeks. The crystalline phases of the metal or metal fluoride synthesized in [BMIm][BF4] were identified by powder X-ray diffraction (PXRD) to exclusively Ni- and Cu-NPs or to solely MF2-NPs for M=Mn, Fe, and Co. The size and size dispersion of the nanoparticles were determined by transmission electron microscopy (TEM) to an average diameter of 2(±2) to 14(±4) nm for the M-NPs, except for the Cu-NPs in PC, which were 51(±8) nm. The MF2-NPs from [BMIm][BF4] were 15(±4) to 65(±18) nm. The average diameter from TEM is in fair agreement with the size evaluated from PXRD with the Scherrer equation. The characterization was complemented by energy-dispersive X-ray spectroscopy (EDX). Electrochemical investigations of the CoF2-NPs as cathode materials for lithium-ion batteries were simply evaluated by galvanostatic charge/discharge profiles, and the results indicated that the reversible capacity of the CoF2-NPs was much lower than the theoretical value, which may have originated from the complex conversion reaction mechanism and residue on the surface of the nanoparticles. [ABSTRACT FROM AUTHOR]

In recent years, the usage of ionic liquids (ILs) in the synthesis of metal oxides has been extensively studied, especially with respect to their possible advantageous effects in comparison to conventional syntheses protocols. Herein, an overview is given on the variety of different syntheses of TiO2-based materials, which correlates to the diversity of different ionic liquids. Special emphasis is put on the historic development of the IL-based synthesis of TiO2 materials in the general context of research on IL-based materials synthesis. Also, the assumed advantages of both, the synthesis and the resulting TiO2 materials, are critically revised. It can be concluded that the application of ILs exerts a direct influence on several parameters, namely the phase composition, the dopants or the nanostructuring of the material. Importantly, the research on TiO2-based materials enables fundamental insights into IL-specific effects in the synthesis of inorganic materials in general. [ABSTRACT FROM AUTHOR]

To gain a deeper understanding of the TiCl 4 solvation effects in multi-component ionic liquids, we performed ab initio molecular dynamics simulations of 1-butyl-3-methylimidazolium [C 4 C 1 Im] + , tetrafluoroborate [BF 4 ] − , chloride [Cl] − both with and without water and titanium tetrachloride TiCl 4 . Complex interactions between cations and anions are observed in all investigated systems. By further addition of water and TiCl 4 this complex interaction network is extended. Observations of the radial distribution functions and number integrals show that water and TiCl 4 not only compete with each other to interact mainly with [Cl] − , which strongly influences the cation-[BF 4 ] − interaction, but also interact with each other, which leads to the fact that in certain systems the cation-anion interaction is enhanced. Further investigations of the Voronoi polyhedra analysis have demonstrated that water has a greater impact on the nanosegregated system than TiCl 4 which is also due to the fact of the shear amount of water relative to all other components and its higher mobility compared to TiCl 4 . Overall, the polar network of the IL mixture collapses by including water and TiCl 4 . In the case of [Cl] − chloride enters the water continuum, while [BF 4 ] − remains largely unaffected, which deeply affects the interaction of the ionic liquid (IL) network. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • TiO 2 nanoparticle multiphase heterojunctions have been prepared from ionic liquids. • Heterojunctions of bronze-TiO 2 and anatase are formed at different ratios. • Control of the TiO 2 (B)/anatase ratio solely by IL mixture. • 3:2 ratio of TiO 2 (B)/anatase exhibits highest hydrogen evolution performance. • Physical mixtures (3:2) cannot compete with the in-situ prepared heterojunction. Abstract We report on the immense influence of interfacial contact on the photocatalytic performance of TiO 2 nanoparticle multiphase heterojunctions. The composition of anatase and TiO 2 (B) in the final nanoparticles can be tuned, depending on the mixture of different Ionic Liquids. A ratio of 3:2 TiO 2 (B) to anatase exhibits the most pronounced enhancement in photocatalytic hydrogen evolution activity. As a comparative study, different physical mixtures in the ratio of 3:2 have been investigated in order to prove the formation of the heterojunction between anatase and TiO 2 (B). None of the physical mixtures can reach similar hydrogen evolution rates as the IL-based, in-situ prepared mixture proving the beneficial impact of interphase connections on charge carrier separation and therefore on photocatalytic efficiency by suppression of charge carrier recombination. [ABSTRACT FROM AUTHOR]

The majority of particle synthesis methods are based on nucleation and growth processes in solvents. Whereas the role of capping agents has been investigated extensively regarding control particle size and shape, the unique role of the solvent is understood to a much lesser extent. Compared to other polar solvents, e.g. water, ionic liquids (ILs) are unique because their properties can be fine-tuned precisely by appropriate choice and modification of cation and anion. This makes ILs also interesting for particle synthesis. We present the generation of zinc oxide (ZnO) in imidazolium ILs starting from molecular precursors. A hydrolytic, sol-gel based synthesis route is suitable to achieve nanocrystalline ZnO. We find by in-situ synchrotron wide angle X-ray diffraction that in ILs an unusual ZnO phase with α-boron nitride structure acts as an intermediate prior to crystallization of the thermodynamically stable Wurtzite. This special mechanism leads to organic-inorganic hybrid IL/ZnO nanoparticles with plate-like morphology. Because of the large content of IL embedded in the ZnO matrix the novel particles gain ionogel properties, e.g. ion conductivity probed by impedance spectroscopy. [ABSTRACT FROM AUTHOR]

We pyrolyzed and activated novolac beads in one single step with ammonia at different temperatures (750–950 °C), which leads to a highly porous carbon with nitrogen-doping. The chemical and physical properties were characterized and correlated with the electrochemical performance as supercapacitor electrodes. The average pore size varied at 0.6–1.4 nm dependent on the synthesis temperatures. Three different electrolytes (aqueous, organic, and an ionic liquid) were tested. The specific capacitance in a symmetrical supercapacitor reached up to 173 F g −1 and was strongly dependent on the porosity of the electrode material and the kind of electrolyte. We found that the presence of nitrogen enhanced the electrochemical performance stability and led to a high specific energy of 50 Wh·kg −1 using an ionic liquid as electrolyte. [ABSTRACT FROM AUTHOR]

In this work, we present detailed investigations on the influence of binary ionic liquid (IL) mixtures on sol-gel syntheses of metastable metal oxide phases. The synthesis of the metastable TiO2 bronze phase and anatase as well as the rutile modification is followed via in situ diffraction methods coupled with thermal gravimetric analysis. The variation of the composition of mixtures of ILs allows for the adjustment of TiO2 phase composition at low temperatures. On the basis of these results, the synthesis of the hexagonal tungsten bronze-like titanium hydroxyl oxy fluoride was achieved. Our results pave the way for a deeper understanding of IL participation in the syntheses of inorganic nanomaterials, going further than treating them as solvents. [ABSTRACT FROM AUTHOR]