Acid gases such as SO 2 can be absorbed by ionic liquids (ILs) because of their unique properties. In this work, we developed a new approach for improving SO 2 absorption by novel acylamido-based anion-functionalized ILs. Several kinds of such ILs with different structures of acylamido group (anionic acylamide) were designed, prepared, and used for efficient capture of SO 2 . It was shown that these acylamido-based ILs strongly interacted with SO 2 , resulting in a very high SO 2 capacity up to ∼4.5 mol SO 2 per mole of IL. The interactions between acylamido-based ILs and SO 2 were investigated by FT-IR, NMR, and quantum chemical calculations. It was found that the dramatic enhancement of SO 2 absorption capacity was originated from the multiple-site interactions such as N···S and CO···S interactions between the anion and SO 2 . Furthermore, the captured SO 2 was easy to release by heating or bubbling N 2 through the SO 2 -saturated ILs. This novel strategy provides an excellent alternative to current SO 2 capture technologies.Controlling and minimizing the emissions of such acid gas as SO 2 are highly important, because SO 2 is a significant source of atmospheric pollution that threatens environment and human health. Novel materials and processes for efficient, reversible and economical capture of SO 2 are highly desired to develop and are of critical importance for environmental protection. Although several conventional removal processes, such as limestone scrubbing and ammonia scrubbing, have been used for flue gas desulfurization (FGD), the inherent disadvantages of these technologies should not be ignored, including the production of large quantities of wastewater and useless byproducts. 1−3Recently, ionic liquids (ILs) have been proposed as better acid gas absorbents due to their unique properties, such as extremely low vapor pressure, wide liquid temperature range, nonflammability, chemical stability, and tunable structure and properties. 4−12 SO 2 has a high solubility in some ILs through physical interaction, 13−15 especially in ether-functionalized ILs. 16,17 However, effective capture of SO 2 from flue gas requires strong interaction between IL and SO 2 because of the relatively low SO 2 partial pressure in this stream. Han et al. 18 reported the first example for chemical absorption of SO 2 by 1,1,3,3-tetramethylguandinium lactate ([TMG][L]), which absorbed about 1.0 mol SO 2 per mole of IL at 1 bar with 8% SO 2 in a gas mixture of SO 2 and N 2 . Since then, other kinds of ILs, such as hydroxyl ammonium ILs, 19,20 imidazolium ILs, 14,21−23 thiocyanate ILs, 24−26 phenolate ILs, 27,28 poly-(ILs), 29,30 and supported IL membranes (SILMs) 31,32 were used to capture and separate SO 2 . Recently, Wang et al. 33−36 reported a new strategy for acid gas absorption by tunable azolate-ILs and found that trihexyl(tetradecyl) phosphonium tetrazolate ([P 66614 ][Tetz]) could capture 3.72 mol SO 2 per mole IL through multiple-site interactions between anion and SO 2 . 33 Other groups studied the performance of car...

Single-atom metal catalysts (SAMCs) have high catalytic activity, but mass production of SAMCs with high metal loading remains challenging. In this work, a two-step and one-pot strategy is presented to prepare mesoporous carbon nitride (CN)-based Cu single-atom catalysts (Cu–CN-x, where x refers to the metal loading in wt %) with ultrahigh metal loadings (e.g., up to 26.6 wt %), in which the mixture of urea and copper chloride is first heated at 180 °C and then calcined at 550 °C. Extended X-ray absorption fine structure analysis demonstrates that a Cu single atom is doped into the skeleton of CN via replacing one carbon atom and bonding with three nitrogen atoms. The resultant Cu–CN-x catalyst displays excellent performance and high stability for catalyzing the reaction of terminal alkynes with atmospheric carbon dioxide, much better than the best reported catalyst, synergistically attributed to both the isolated Cu single atom and porous structure of the support. Density functional theory calculation shows that the reaction between CO2 and deprotonated phenylacetylene is energetically exothermic on Cu–CN with a reaction energy of about −0.27 eV and an energy barrier of +0.85 eV. This synthetic strategy paves a universal way for mass production of SAMCs with high-density metal loadings.

A new approach has been developed to improve SO2 sorption by cyano-containing ionic liquids (ILs) through tuning the basicity of ILs and cyano-sulfur interaction. Several kinds of cyano-containing ILs with different basicity were designed, prepared, and used for SO2 capture. The interaction between these cyano-containing ILs and SO2 was investigated by FTIR and NMR methods. Spectroscopic investigations and quantum chemical calculations showed that dramatic effects on SO2 capacity originate from the basicity of the ILs and enhanced cyano-sulfur interaction. Furthermore, the captured SO2 was easy to release by heating or bubbling N2 through the ILs. This efficient and reversible process, achieved by tuning the basicity of ILs, is an excellent alternative to current technologies for SO2 capture.

O-heterocycles have wide applications, and their efficient and green synthesis is very interesting. Herein, we report hydrogen-bonding catalyzed ring-closing metathesis of aliphatic ethers to O-heterocycles over ionic liquid (IL) catalyst under metal-and solvent-free conditions. The IL 1butylsulfonate-3-methylimidazolium trifluoromethanesulfonate ([SO 3 H-BMIm][OTf]) is discovered to show outstanding performance, better than the reported catalysts. An interface effect plays an important role in mediating the reaction rate due to the immiscibility between the products and the IL catalyst, and the products can be spontaneously separated. NMR analysis and DFT calculation suggest that a pair of cation and anion of [SO 3 H-BMIm][OTf] could form three strong Hbonds with an ether molecule, which catalyze the ether transformation via a cyclic oxonium intermediate. A series of O-heterocycles including tetrahydrofurans, tetrahydropyrans, morpholines and dioxane can be obtained from their corresponding ethers in excellent yields (e.g., > 99 %). This work opens an efficient and metal-free way to produce O-heterocycles from aliphatic ethers.

Perfluorinated covalent triazine frameworks (F-CTFs) have shown unique features and attractive performance in separation and catalysis. However, state-of-the-art F-CTFs synthesized via the ZnCl 2 -promoted procedure have quite low fluorine contents due to C À F bond cleavage induced by chloride (a Lewis base) and the harsh conditions deployed (400-700 8C). Fabricating F-CTFs with high fluorine contents (> 30 wt %) remains challenging. Herein, we present a lowtemperature ionothermal approach (275 8C) to prepare F-CTFs, which is achieved via polymerization of tetrafluoroterephthalonitrile (TFPN) over the Lewis superacids, e.g., zinc triflimide [Zn(NTf 2 ) 2 ] without side reactions. With low catalyst loading (equimolar), F-CTFs are afforded with high fluorine content (31 wt %), surface area up to 367 m 2 g À1 , and micropores around 1.1 nm. The highly hydrophobic F-CTF-1 exhibits good capability to boost electroreduction of CO 2 to CO, with faradaic efficiency of 95.7 % at À0.8 V and high current density (À141 mA cm À2 ) surpassing most of the metal-free electrocatalysts.

Dehydrative cyclization of diols to O-heterocycles is attractive, but acid and/or metal-based catalysts are generally required. Here, we present a hydrogen-bond donor and acceptor cooperative catalysis strategy for the synthesis of O-heterocycles from diols in ionic liquids [ILs; e.g., 1-hydroxyethyl-3-methyl imidazolium trifluoromethanesulfonate ([HO-EtMIm][OTf])] under metal-free, acid-free, and mild conditions. [HO-EtMIm][OTf] is tolerant to a wide diol scope, shows performance even better than H2SO4, and affords a series of O-heterocycles including tetrahydrofurans, tetrahydropyrans, morpholines, dioxanes, and thioxane in high yields. Mechanism investigation indicates that the IL cation and anion serve as hydrogen-bond donor and acceptor, respectively, to activate the C─O and O─H bonds of alcohol via hydrogen bonds, which synergistically catalyze dehydrative cyclization of diols to O-heterocycles. Notably, the products could be spontaneously separated after reaction because of their immiscibility with the IL, and the IL could be recycled. This green strategy has great potential for application in industry.

Because of the unique properties of ionic liquids, it has been suggested that ionic liquids, especially functionalized ionic liquids, could be used as good solvents for the capture of acidic gases such as SO 2 .In this work, a kind of carboxylate ionic liquid with a halogen atom on the alkyl chain of the carboxylate anion was developed for highly efficient and reversible capture of SO 2 through multiple-site interactions.It was found that these halogenated carboxylate ionic liquids improved SO 2 capture performance as well as being reversible. Spectroscopic investigations and quantum chemical calculations show that the enhancement in SO 2 capacity originated from the halogen sulfur interaction between the halogen group on the carboxylate anion and SO 2 . Furthermore, the captured SO 2 was easy to release by heating or bubbling N 2 through the SO 2 -saturated ionic liquids. This highly efficient and reversible process using halogenated carboxylate ionic liquids through adding a halogen group to the carboxylate anion provides an excellent alternative to current SO 2 capture technologies.Scheme 1 The structures of the cation and the halogenated carboxylate anions employed in this work for SO 2 capture.60976 | RSC Adv., 2015, 5, 60975-60982This journal is

Electric double layer capacitors (EDLCs) usually show high rate performance and long cycling spans but inferior specific capacitance, which are mainly created by restriction of the charge storage mechanism. To improve the capacitive performance, traditional methods include enlarging surface area, optimizing porous structures, and readjusting functional groups through heteroatom doping to electrode materials. Besides that, another promising approach is suggested, which is to enhance surface roughness of the electrode materials for ion storage and transport. To prove this view, two porous carbon materials were fabricated by activation–calcination methods, which allowed the materials to have identical surface area, porous structures, and surface composition but the surface roughness. Further electrochemical measurements exhibited that the optimal sample with higher roughness has remarkable specific capacitance (up to 562 F g–1), and the increment rate is more than 50% when compared with contrast sample (367 F g–1). Therefore, optimization of the surface roughness of electrode materials is another efficient route to make robust EDLCs.