A Bifunctional Ionic Liquid for Capture and Electrochemical Conversion of CO2 to CO over Silver,ACS Catalysis

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A Bifunctional Ionic Liquid for Capture and Electrochemical Conversion of CO2 to CO over Silver
ACS Catalysis ( IF 11.3 ) Pub Date : 2023-05-25 , DOI: 10.1021/acscatal.3c01538
Saudagar Dongare ₁ , Oguz Kagan Coskun ₁ , Eda Cagli ₁ , Kevin Y C Lee ₂ , Guodong Rao ₂ , R David Britt ₂ , Louise A Berben ₂ , Burcu Gurkan ₁

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Electrochemical conversion of CO₂ requires selective catalysts and high solubility of CO₂ in the electrolyte to reduce the energy requirement and increase the current efficiency. In this study, the CO₂ reduction reaction (CO₂RR) over Ag electrodes in acetonitrile-based electrolytes containing 0.1 M [EMIM][2-CNpyr] (1-ethyl-3-methylimidazolium 2-cyanopyrolide), a reactive ionic liquid (IL), is shown to selectively (>94%) convert CO₂ to CO with a stable current density (6 mA·cm^–2) for at least 12 h. The linear sweep voltammetry experiments show the onset potential of CO₂ reduction in acetonitrile shifts positively by 240 mV when [EMIM][2-CNpyr] is added. This is attributed to the pre-activation of CO₂ through the carboxylate formation via the carbene intermediate of the [EMIM]⁺ cation and the carbamate formation via binding to the nucleophilic [2-CNpyr]⁻ anion. The analysis of the electrode–electrolyte interface by surface-enhanced Raman spectroscopy (SERS) confirms the catalytic role of the functionalized IL where the accumulation of the IL-CO₂ adduct between −1.7 and −2.3 V vs Ag/Ag⁺ and the simultaneous CO formation are captured. This study reveals the electrode surface species and the role of the functionalized ions in lowering the energy requirement of CO₂RR for the design of multifunctional electrolytes for the integrated capture and conversion.

中文翻译：

用于在银上捕获 CO2 并将其电化学转化为 CO 的双功能离子液体

CO ₂的电化学转化需要选择性催化剂和CO ₂在电解质中的高溶解度，以减少能量需求并提高电流效率。在本研究中，在含有 0.1 M [EMIM][2-CNpyr]（1-乙基-3-甲基咪唑鎓 2-氰基吡咯）（一种反应性_离子液体）的乙腈基电解质中，在银电极上发生 CO ₂还原反应 (CO 2 RR) (IL)，显示可以在至少12小时内以稳定的电流密度(6 mA·cm ^–2 )选择性地(>94%)将CO ₂转化为CO。线性扫描伏安实验表明，当添加[EMIM][2-CNpyr]时，乙腈中CO ₂还原的起始电位正移240 mV。这归因于CO ₂通过[EMIM] ⁺阳离子的卡宾中间体形成羧酸盐以及通过与亲核[2-CNpyr] ^-阴离子结合形成氨基甲酸盐而预活化。通过表面增强拉曼光谱 (SERS) 对电极-电解质界面的分析证实了功能化 IL 的催化作用，其中 IL-CO ₂加合物在 -1.7 和 -2.3 V vs Ag/Ag ⁺之间积累，同时CO 的形成被捕获。这项研究揭示了电极表面物种和功能化离子在降低 CO ₂ RR 能量需求方面的作用，以设计用于集成捕获和转化的多功能电解质。

更新日期：2023-05-25

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