Electrochemical reduction of CO2 in [NH2-emim]Br/[Bmim]BF4 ionic liquid composite
【Abstract】Amine-functionalized ionic liquid, 1-(2-aminoethyl)-3-methylimidazolium bromide ([NH2-emim]Br), was synthesized from 2-bromoethylamine hydrobromide and N-methyl imidazole salt at reflux condition and characterized by 1H NMR and IR. The viscosity, electrical conductivity and saturated carbon dioxide solubility in [NH2-emim]Br ionic liquid measured at 25 °C were 26.691 Pa·s, 0.113 0 mS·cm−1 and 82% by molar ratio, respectively. Binary ionic liquid composites of [NH2-emim]Br/[Emim]BF4, [NH2-emim]Br/[Bmim]BF4, and [NH2-emim]Br/[Bmim]PF6 were prepared at different mass ratios and used for electrochemical reduction of CO2. The results of cyclic voltammetry at room temperature showed that thepeak current of CO2 reduction in [NH2-emim]Br(0.5%)-[Bmim]BF4 was increased by about 9 times compared with that in [Bmim]BF4 and the reduction peak potential was shifted positively by 0.4 V. With viscosity decrease to 0.082 27 Pa·s and electrical conductivity increase to 1.317 mS·cm−1, the binary ionic liquid composite is a good ionic liquid system for CO2 electrochemical reduction.
【Keywords】 carbon dioxide; ionic liquids; binary mixture; electrochemistry; cyclic voltammetry;
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