No abstract

The production of carbonates from carbon dioxide (CO2) and epoxides is an atom-economical reaction. This study developed a series of poly­(ionic liquids) (PILs) by copolymerizing a novel functional ionic liquid (ethyl ether bis­(1-vinylimidazolium) chloride) with ethylene glycol dimethacrylate (EGDMA). The structures and morphologies of PILs were investigated by adjusting the mole ratio between IL and EGDMA in the PILs. The prepared PILs were investigated as catalysts for the cycloaddition of CO2 with epoxides, and they show improved catalytic efficiency and accelerated mass transfer rate due to their mesoporous structure with a large number of uniformly distributed active ion sites. The PIL was stable, and the activity remained unchanged during the recycling of CO2 cycloaddition to epoxides under mild conditions without any solvent and co-catalyst. This study emphasizes the PIL as a versatile platform to obtain cyclic carbonates from CO2 under mild conditions.

Water electrolysis offers a promising approach toward future sustainable energy mix utilizing hydrogen as energy carrier. Bifunctional catalyst which is active in both oxygen and hydrogen evolution reactions can significantly enhance total electrochemical water splitting efficiency and simplify electrolysis systems. In this study, nitrogen doped nickel-containing porous carbon networks were prepared to fulfill this role. Peptone was used as carbon and nitrogen source during the synthesis and NaCl presence as a template resulted in the formation of open mesopores interconnected by thin carbon sheets with nanosized Ni particles encapsulated in the carbon matrix. A low onset potential of 53 mV and a charge transfer resistance of 3.8 Ω with excellent cycling stability were demonstrated when the optimized catalyst Ni-2 was applied in HER. It was also shown that Ni-2 onset potential, charge transfer resistance, and durability in OER were comparable to those of a commercial RuO2 catalyst. During the electrolysis study conducted at 10 mA cm–2, Ni-2 maintained a cell voltage of 1.63 V with remarkable stability during 25 h operation.

Porous Ni(OH)2 nanoflakes are directly grown on the surface of nickel foam supported Ni3Se2 nanowire arrays using an in situ growth procedure to form 3D Ni3Se2@Ni(OH)2 hybrid material. Owing to good conductivity of Ni3Se2, high specific capacitance of Ni(OH)2 and its unique architecture, the obtained Ni3Se2@Ni(OH)2 exhibits a high specific capacitance of 1689 µAh cm−2 (281.5 mAh g−1) at a discharge current of 3 mA cm−2 and a superior rate capability. Both the high energy density of 59.47 Wh kg−1 at a power density of 100.54 W kg−1 and remarkable cycling stability with only a 16.4% capacity loss after 10 000 cycles are demonstrated in an asymmetric supercapacitor cell comprising Ni3Se2@Ni(OH)2 as a positive electrode and activated carbon as a negative electrode. Furthermore, the cell achieved a high energy density of 50.9 Wh L−1 at a power density of 83.62 W L−1 in combination with an extraordinary coulombic efficiency of 97% and an energy efficiency of 88.36% at 5 mA cm−2 when activated carbon is replaced by metal hydride from a commercial NiMH battery. Excellent electrochemical performance indicates that Ni3Se2@Ni(OH)2 composite can become a promising electrode material for energy storage applications.

Although separation of phenolic compounds from coal tar has a good practical application value in industry, the traditional separation method can result in serious environmental problems. In the present work, three ionic liquids (ILs) with dual Lewis basic sites were designed and synthesized by neutralizating 1,1,3,3-tetramethylguanidine (TMG) and corresponding acids (L-proline, acetate acid, and tetrafluoroboric acid), which were employed to separate phenolic compounds from the model oil and coal tar. The basicity of TMG-based ILs were characterized by a probe molecule through 1H NMR and quantum chemical calculations. Moreover, the influence of factors on the separation efficiency, such as stirring time, extraction temperature, and the ratio of ILs to model oil, was investigated in detail. The results showed that [TMG]­[BF4] showed the best extraction efficiency of 98.2%, at a extraction temperature of 30 °C, stirring time of 35 min, and extraction ratio of 1.1 g/4 mL. After being separated, these ILs were recovered through back extraction. Furthermore, the separation mechanism was determined by analyzing the hydrogen bond and chemical bond for ILs and phenolic compounds via UV–vis, FT-IR, and quantum chemical calculations. Thus, TMG-based ILs can be effective in separating phenolic compounds from coal tar and as an alternative extractant in the future.