Utilization of ionic liquids (ILs) in material synthesis is a promising field. The unusual properties of ILs provide new opportunities for the design of functional materials, and much excellent work has been reported. Here, the progress in material design and synthesis using ILs, especially nanomaterials, is discussed, including the unitization of ILs as synthetic media, templates, precursors, or components in the synthesis of various categories of nanomaterials. The challenges and opportunities in this interesting and rapid developing area are also discussed.

The effect of water on CO₂ hydrogenation to produce higher alcohols (C₂–C₄) was studied. Pt/Co₃O₄, which had not been used previously for this reaction, was applied as the heterogeneous catalyst. It was found that water and the catalyst had an excellent synergistic effect for promoting the reaction. High selectivity of C₂–C₄ alcohols could be achieved at 140 °C (especially with DMI (1,3-dimethyl-2-imidazolidinone) as co-solvent), which is a much lower temperature than reported previously. The catalyst could be reused at least five times without reducing the activity and selectivity. D₂O and ¹³CH₃OH labeling experiments indicated that water involved in the reaction and promoted the reaction kinetically, and ethanol was formed via CH₃OH as an intermediate.

Highly efficient electrochemical reduction of CO₂ into value-added chemicals using cheap and easily prepared electrodes is environmentally and economically compelling. The first work on the electrocatalytic reduction of CO₂ in ternary electrolytes containing ionic liquid, organic solvent, and H₂O is described. Addition of a small amount of H₂O to an ionic liquid/acetonitrile electrolyte mixture significantly enhanced the efficiency of the electrochemical reduction of CO₂ into formic acid (HCOOH) on a Pb or Sn electrode, and the efficiency was extremely high using an ionic liquid/acetonitrile/H₂O ternary mixture. The partial current density for HCOOH reached 37.6 mA cm⁻² at a Faradaic efficiency of 91.6 %, which is much higher than all values reported to date for this reaction, including those using homogeneous and noble metal electrocatalysts. The reasons for such high efficiency were investigated using controlled experiments.

Methanol is a very useful platform molecule and liquid fuel. Electrocatalytic reduction of CO₂ to methanol is a promising route, which currently suffers from low efficiency and poor selectivity. Herein we report the first work to use a Mo-Bi bimetallic chalcogenide (BMC) as an electrocatalyst for CO₂ reduction. By using the Mo-Bi BMC on carbon paper as the electrode and 1-butyl-3-methylimidazolium tetrafluoroborate in MeCN as the electrolyte, the Faradaic efficiency of methanol could reach 71.2 % with a current density of 12.1 mA cm⁻², which is much higher than the best result reported to date. The superior performance of the electrode resulted from the excellent synergistic effect of Mo and Bi for producing methanol. The reaction mechanism was proposed and the reason for the synergistic effect of Mo and Bi was discussed on the basis of some control experiments. This work opens a way to produce methanol efficiently by electrochemical reduction of CO₂.

The properties of supported non-noble metal particles with a size of less than 1 nm are unknown because their synthesis is a challenge. A strategy has now been created to immobilize ultrafine non-noble metal particles on supports using metal–organic frameworks (MOFs) as metal precursors. Ni/SiO₂ and Co/SiO₂ catalysts were synthesized with an average metal particle size of 0.9 nm. The metal nanoparticles were immobilized uniformly on the support with a metal loading of about 20 wt %. Interestingly, the ultrafine non-noble metal particles exhibited very high activity for liquid-phase hydrogenation of benzene to cyclohexane even at 80 °C, while Ni/SiO₂ with larger Ni particles fabricated by a conventional method was not active under the same conditions.

The effect of water on CO₂ hydrogenation to produce higher alcohols (C₂–C₄) was studied. Pt/Co₃O₄, which had not been used previously for this reaction, was applied as the heterogeneous catalyst. It was found that water and the catalyst had an excellent synergistic effect for promoting the reaction. High selectivity of C₂–C₄ alcohols could be achieved at 140 °C (especially with DMI (1,3-dimethyl-2-imidazolidinone) as co-solvent), which is a much lower temperature than reported previously. The catalyst could be reused at least five times without reducing the activity and selectivity. D₂O and ¹³CH₃OH labeling experiments indicated that water involved in the reaction and promoted the reaction kinetically, and ethanol was formed via CH₃OH as an intermediate.

Highly efficient electrochemical reduction of CO₂ into value-added chemicals using cheap and easily prepared electrodes is environmentally and economically compelling. The first work on the electrocatalytic reduction of CO₂ in ternary electrolytes containing ionic liquid, organic solvent, and H₂O is described. Addition of a small amount of H₂O to an ionic liquid/acetonitrile electrolyte mixture significantly enhanced the efficiency of the electrochemical reduction of CO₂ into formic acid (HCOOH) on a Pb or Sn electrode, and the efficiency was extremely high using an ionic liquid/acetonitrile/H₂O ternary mixture. The partial current density for HCOOH reached 37.6 mA cm⁻² at a Faradaic efficiency of 91.6 %, which is much higher than all values reported to date for this reaction, including those using homogeneous and noble metal electrocatalysts. The reasons for such high efficiency were investigated using controlled experiments.

Methanol is a very useful platform molecule and liquid fuel. Electrocatalytic reduction of CO₂ to methanol is a promising route, which currently suffers from low efficiency and poor selectivity. Herein we report the first work to use a Mo-Bi bimetallic chalcogenide (BMC) as an electrocatalyst for CO₂ reduction. By using the Mo-Bi BMC on carbon paper as the electrode and 1-butyl-3-methylimidazolium tetrafluoroborate in MeCN as the electrolyte, the Faradaic efficiency of methanol could reach 71.2 % with a current density of 12.1 mA cm⁻², which is much higher than the best result reported to date. The superior performance of the electrode resulted from the excellent synergistic effect of Mo and Bi for producing methanol. The reaction mechanism was proposed and the reason for the synergistic effect of Mo and Bi was discussed on the basis of some control experiments. This work opens a way to produce methanol efficiently by electrochemical reduction of CO₂.

The properties of supported non-noble metal particles with a size of less than 1 nm are unknown because their synthesis is a challenge. A strategy has now been created to immobilize ultrafine non-noble metal particles on supports using metal–organic frameworks (MOFs) as metal precursors. Ni/SiO₂ and Co/SiO₂ catalysts were synthesized with an average metal particle size of 0.9 nm. The metal nanoparticles were immobilized uniformly on the support with a metal loading of about 20 wt %. Interestingly, the ultrafine non-noble metal particles exhibited very high activity for liquid-phase hydrogenation of benzene to cyclohexane even at 80 °C, while Ni/SiO₂ with larger Ni particles fabricated by a conventional method was not active under the same conditions.

Transformation of anisole (methoxybenzene), a typical component of bio-oil, into phenol and methylated phenols was studied over HY zeolites with framework Si/Al ratios of 5, 15, 25, and 35. It was demonstrated that the amounts of Brønsted acid and Lewis acid sites, the ratio of Lewis acid and Brønsted acid sites, and the textural properties of the zeolites were all crucial parameters that influenced the catalytic performance. The Brønsted acid and Lewis acid sites of the zeolites catalyzed the reaction cooperatively and efficiently promoted the transmethylation. The hierarchical channel system with fully open micropore–mesopore connectivity was favorable to reduce the amount of coke generated.

Supported vanadium oxides (V_xO_y) on hydrophobic poly(ionic liquid)s (PILs), for which the PILs were obtained by copolymerization of the ionic liquid (IL) 1-hexadecyl-3-vinylimidazolium bromide and the cross-linker divinylbenzene (DVB), are reported. The V_xO_y/PIL catalyst was characterized by different techniques, and the performance of the catalyst for the selective oxidation of benzene to phenol was studied with H₂O₂ as the oxidant. It was demonstrated that V_xO_y/PIL had much better catalytic performance than the analogous catalyst V_xO_y/P, prepared with the polymer support (P) obtained from DVB and vinyl imidazole, without the IL. The high activity and selectivity of the V_xO_y/PIL catalyst could be attributed to the incorporation of the IL during the polymerization, which endowed the V_xO_y/PIL catalyst with increased specific surface area, stronger absorbent ability, and more active sites than the smooth and bulky V_xO_y/P. Furthermore, the hydrophobic side chain of the IL in the catalyst was beneficial for the access of benzene and the removal of the generated phenol from the surface of the catalyst, which also played an important role in improving the catalytic performance of V_xO_y/PIL. Up to 13.4 % yield of phenol was achieved, with a high selectivity of 97.5 %. In addition, the catalyst could be easily separated and recycled at least three times without significant decline in the phenol yield.

Ionic liquids (ILs) have attracted much attention due to their unique properties and wide application potential in a variety of fields. The unusual properties of ILs provide numerous opportunities to design and prepare arious advanced materials, including highly efficient catalysts. In recent years, synthesis of different kinds of catalytic materials and their applications in chemical reactions have been studied extensively and have become a very interesting area. Herein, we present a review on the synthesis of catalytic materials using ILs as the media and/or functional components; the important and widely investigated topics are discussed, including mainly metal nanocatalysts/IL, functional IL/support, metals or metal oxides/IL/support, polymeric ILs (PILs) catalysts, and the performances of catalytic systems are highlighted. An outlook for this interesting area is also given at the end of the article.

Al₂O₃ or SiO₂ particles with abundant surface hydroxyl groups can prevent side reactions of aromatic compounds with AlCl₃ completely; this Lewis acid can potentially destroy the stable structure of aromatic compounds to a large extent. This discovery was successfully utilized in the highly efficient hydrogenation of benzene, toluene, and naphthalene under mild conditions co-catalyzed by AlCl₃ and Pd/Al₂O₃ or Pd/SiO₂. Pd, AlCl₃, and the surface hydroxyl groups on the support show excellent cooperative effects for the hydrogenation reactions. Theoretical studies indicate that formation of a complex, by an interaction between benzene, AlCl₃, and the solid oxides, plays a key role in the highly efficient hydrogenation reactions.

Design and preparation of efficient and economical catalysts for direct hydroxylation of benzene to phenol is an important topic. In this work, a series of metal-doped graphitic carbon nitride catalyst (Cu-, Fe-, V-, Co-, and Ni-g-C₃N₄) were successfully synthesized by using urea as the precursor through a facile and efficient method. The catalysts were characterized systematically using N₂ adsorption–desorption, FTIR, thermogravimetric analysis, powder X-ray diffraction, and X-ray photoelectron spectroscopy techniques. It was found that the vanadium-doped graphitic carbon nitride catalyst V-g-C₃N₄ was the most efficient catalyst for the direct synthesis of phenol from benzene with hydrogen peroxide as the oxidant and it could be recycled at least 4 times. The influence of reaction conditions such as the solvent, reaction temperature, reaction time, and the amounts of catalyst and hydrogen peroxide were investigated. Under optimized conditions, 18.2 % yield of phenol was obtained with the selectivity to phenol as high as 100 %.

Emission of SO₂ in flue gas from the combustion of fossil fuels leads to severe environmental problems. Exploration of green and efficient methods to capture SO₂ is an interesting topic, especially at lower SO₂ partial pressures. In this work, ionic liquids (ILs) 1-(2-diethylaminoethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Et₂NEMim][Tf₂N]) and 1-(2-diethylaminoethyl)-3-methylimidazolium tetrazolate ([Et₂NEMim][Tetz]) were synthesized. The performances of the two ILs to capture SO₂ were studied under different conditions. It was demonstrated that the ILs were very efficient for SO₂ absorption. The [Et₂NEMim][Tetz] IL designed in this work could absorb 0.47 g g_IL⁻¹ at 0.0101 MPa SO₂ partial pressure, which is the highest capacity reported to date under the same conditions. The main reason for the large capacity was that both the cation and the anion could capture SO₂ chemically. In addition, the IL could easily be regenerated, and the very high absorption capacity and rapid absorption/desorption rates were not changed over five repeated cycles.

Development of efficient catalysts for the dehydration of carbohydrates to produce 5-hydroxymethylfurfural (HMF) is a very attractive topic. In this work, dehydration of fructose catalyzed by three organic molecules, including hexachlorotriphosphazene (N₃P₃Cl₆), trichloromelamine (C₃N₆H₃Cl₃) and N-bromosuccinimide (NBS), was studied in ionic liquids. It was discovered that the three organic molecules had high activity in accelerating the dehydration of fructose and N₃P₃Cl₆ was the most efficient catalyst among them. The effects of amount of catalysts, temperature, solvents, reaction time, and substrate/solvent weight ratio on the reaction were investigated using N₃P₃Cl₆ as the catalyst and 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) as the solvent. It was demonstrated that the N₃P₃Cl₆/[Bmim]Cl catalytic system was very effective for catalyzing the reaction. The yield of HMF could reach 92.8% in 20 min at the optimized conditions and the N₃P₃Cl₆/[Bmim]Cl system could be reused. Further study indicated that the N₃P₃Cl₆/[Bmim]Cl system was also effective for the dehydration of sucrose and inulin and satisfactory yield could be obtained at suitable conditions.

Clays are very promising, environmentally benign catalyst supports. Herein, Ru–Cd/bentonite (BEN) catalysts were prepared and characterized by TEM, SEM, XPS, and XRD. The as-prepared catalysts were used to catalyze the selective hydrogenation of benzene into cyclohexene with different Ru/Cd molar ratios, hydrogen pressures, and reaction temperatures. We found that the catalytic activity decreased with decreasing Ru/Cd molar ratio, whereas the selectivity was enhanced. The most-favorable Ru/Cd molar ratio was 1 and the optimal hydrogen pressure and temperature were 5 MPa and 150 °C, respectively. The yield of cyclohexene reached 24.8 % over Ru–Cd/BEN under the optimal reaction conditions without the need for any additives in the reaction system and this catalyst could be reused several times in the reaction without a drop in the yield of cyclohexene. The Cd in the catalyst enhanced the selectivity for cyclohexene. Furthermore, Cd/BEN could be used an as effective supported additive to promote the hydrogenation of benzene into cyclohexene catalyzed by Ru/BEN or Ru/SBA-15.

Exploration of new and effective routes to conduct organic reactions in water using the special properties of water/organics is of great importance. In this work, we performed the disproportionation of various aromatic alcohols in water and in different organic solvents. It was demonstrated that the disproportionation reactions of the alcohols were accelerated more effectively in water than organic-solvent-based or solvent-free reactions. A series of control experiments were conducted to study the mechanism of the accelerated reaction rate in water. It was shown that the reactants could emulsify the reactant/water systems at the reaction conditions owing to their amphiphilic nature. The regularly orientated reactant molecules at the water/reactant droplet interface improved the contact probability of the reactive groups and the Pd nanocatalysts, which is one of the main reasons for the enhanced reaction rate in water. Controlling the self-emulsification of amphiphilic reactant/water systems has great application potential for optimizing the rate and/or selectivity of many organic reactions.

The micellization of amphiphilic molecules is an interesting topic from both theoretical and practical points of view. Herein we have studied the effects of compressed CO₂ on the micellization of Pluronics in water by means of fluorescence, UV/Vis spectra, and small-angle X-ray scattering. It was found that CO₂ can induce the micellization of Pluronics in water, and the micelle can return to the initial state of molecular dispersion after depressurization. Therefore, the micellization of Pluronics in water can be switched through the easy control of pressure. Different from the common micelles with hydrophobic cores, interestingly, this CO₂-induced micelle has an amphiphilic core, in which hydrophobic and hydrophilic domains coexist. On account of the ability to dissolve both polar and nonpolar components in the micellar core, the CO₂-induced micelles can improve the reagent compatibilities frequently encountered in various applications. In an attempt to address this advantage, this micelle was utilized as template to the one-step synthesis of Au/silica core–shell composite nanoparticles. Furthermore, the underlying mechanism for the CO₂-induced micellization of Pluronics in water was investigated by a series of experiments.

Efficient conversion of polynuclear aromatic hydrocarbons (PAHs) into liquid fuels is crucial for the hydrocracking processes of heavy oils. In this work, we found that the hydrocracking of anthracene catalyzed by NiFe/HZSM-5 could produce ethyl biphenyl (EB), which realizes high efficiency of hydrocracking of anthracene analogous to its central-ring hydrocracking. More interestingly, addition of water could increase the yield of EB significantly, and the yield of EB could be as high as 34 %. A pathway for hydrocracking of anthracene to EB and the mechanism for water to enhance the yield of EB are proposed on the basis of control experiments. Furthermore, our work demonstrated that water could also increase the liquid yields and reduce the gaseous yields in the hydrocracking of the Daqing residue oil in the same reaction system. This work not only provides new chemical knowledge on hydrocracking of PAHs, but also provides very important information for improving the hydrocracking processes of heavy oils to obtain more liquid fuels with less hydrogen consumption.

The study of the micelle-to-vesicle transition (MVT) is of great importance from both theoretical and practical points of view. Herein, we studied the effect of compressed CO₂ on the aggregation behavior of dodecyltrimethylammonium bromide (DTAB)/sodium dodecyl sulfate (SDS) mixed surfactants in aqueous solution by means of direct observation, turbidity and conductivity measurements, steady-state fluorescence, time-resolved fluorescence quenching (TRFQ), fluorescence quantum yield, and template methods. Interestingly, all these approaches showed that compressed CO₂ could induce the MVT in the surfactant system, and the vesicles returned to the micelles simply by depressurization; that is, CO₂ can be used to switch the MVT reversibly by controlling pressure. Some other gases, such as methane, ethylene, and ethane, could also induce the MVT of the surfactant solution. A possible mechanism is proposed on the basis of the packing-parameter theory and thermodynamic principles. It is shown that the mechanism of the MVT induced by a nonpolar gas is different from the MVT induced by polar and electrolyte additives.