电解液组成对CO_2电化学还原效率的影响

Effects of Electrolyte Solution Composition on Efficiency of CO_2 Electrochemical Reduction

为了考察电解液组成(溶剂和支持电解质)对CO_2电还原效率的影响,以金属银为工作电极,在三电极电解槽中进行了恒电位电解及循环伏安扫描实验。结果表明:相比于二甲基甲酰胺(DMF)和甲醇,用乙腈作溶剂时产物CO法拉第效率最高;强酸作为阳极液支持电解质可以降低CO_2还原过电位并提高CO部分电流密度;离子液体作为阴极液支持电解质可以全面提高CO_2还原效率。研究不同离子液体的催化行为,发现离子液体中阳离子部分对CO部分电流密度的影响比阴离子的影响更明显,进一步证实了咪唑阳离子对还原CO_2起主要催化作用。

In order to investigate the effects of solvent and supporting electrolyte on the electroreduction ofCO2, the constant potential electrolysis (CPE) and cyclic voltammetry (CV) experiments were conducted onAg electrode in a three-electrode electrolytic cell. The results showed that the Faradic efficiency of COobtained in acetonitrile was the highest compared to those in methanol and DMF. The overpotential of CO2reduction decreased and the partial current density of CO(CDCO) increased when strong acid was used as thesupporting electrolyte in the anolyte. The overall efficiency of CO2 reduction was further enhanced when theionic liquid (IL) was used as the supporting electrolyte in the catholyte. Comparing the performances ofvarious ionic liquids on CO2 reduction, it was found that the cationic group in IL had much more significantimpact on the value of CDCO than that of the anionic group. Based on these observations, it could beconfirmed that it was the imidazole cation that played the major catalytic role .