CO 2 reduction reactions (CO 2 RR) are interesting for power‐to‐x applications and have been studied on Pt electrodes in 1‐ethyl‐3‐methylimidazolium dicyanamide [EMIM][DCA] as well as in 1‐ethyl‐3‐methylimidazolium [EMIM][BF 4 ], 1‐butyl‐3‐methylimidazolium [BMIM][BF 4 ] and 1‐ocytl‐3‐methylimidazolium tetrafluoroborate [OMIM][BF 4 ] electrolytes. Cyclic voltammetry indicates a strong increase of activity for CO 2 RR with water concentration which was investigated on molecular level using IR absorption spectroscopy (IRAS) and sum‐frequency generation (SFG) to address both bulk and surface‐adsorbed species. IRAS demonstrates that the formation of an imidazole carboxylic acid intermediate occurs at electrode potentials as high as ‐0.4 V which depend on the choice of the RTIL and the water concentration. In addition, SFG spectroscopy provides evidence for the formation of CO on Pt atop sites and was used to determine the onset potential for the formation CO. In [BMIM][BF 4 ] and [OMIM][BF 4 ] electrolytes, the formation of CO is negligible even at very negative potentials of ‐1.5 V, but for [EMIM][DCA] and [EMIM][BF 4 ] the formation of CO is observed and the onset potential shifts significantly with the H 2 O concentration. Taking the Stark tuning rate (40 cm ‐1 /V) of the CO band into account, we conclude that the CO coverage is fairly low, yet the presence of CO leads to deactivation of the Pt surface and to a decrease in reduction currents.

中文翻译：

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H2O在咪唑室温离子液体中铂/电解质界面处的CO2还原反应中的作用

CO 2还原反应（CO 2 RR）对于power-to-x应用很有趣，并且已经在1-乙基-3-甲基咪唑鎓双氰胺[EMIM] [DCA]和1-乙基-3-甲基吡啶的Pt电极上进行了研究。甲基咪唑鎓[EMIM] [BF 4]，1-丁基-3-甲基咪唑鎓[BMIM] [BF 4]和1-辛基-3-甲基咪唑鎓四氟硼酸酯[OMIM] [BF 4]电解质。循环伏安法表明，CO 2 RR的活性随水浓度的增加而大大增加，这是在分子水平上使用IR吸收光谱法（IRAS）和和频产生法（SFG）在分子水平上进行研究的，以解决体积和表面吸附物质的问题。IRAS表明，咪唑羧酸中间体的形成在电极电势高达-0.4 V时发生，这取决于RTIL的选择和水的浓度。此外，SFG光谱提供了在Pt顶部位点上形成CO的证据，并用于确定形成CO的起始电位。在[BMIM] [BF 4]和[OMIM] [BF 4]电解质中，CO的形成可忽略不计即使在极低的电位（-1.5 V）下，但对于[EMIM] [DCA]和[EMIM] [BF 4]来说，都会观察到CO的形成，并且起始电位随H 2 O浓度的变化而显着变化。考虑到CO谱带的Stark调谐速率（40 cm -1 / V），我们得出的结论是，CO的覆盖率很低，但是CO的存在会导致Pt表面失活并降低还原电流。即使在非常低的电位-1.5 V时，CO的形成也可以忽略不计，但是对于[EMIM] [DCA]和[EMIM] [BF 4]来说，观察到了CO的形成，并且起始电势随着H 2 O浓度的变化而显着变化。考虑到CO谱带的Stark调谐速率（40 cm -1 / V），我们得出的结论是，CO的覆盖率很低，但是CO的存在会导致Pt表面失活并降低还原电流。即使在非常低的电位-1.5 V时，CO的形成也可以忽略不计，但是对于[EMIM] [DCA]和[EMIM] [BF 4]来说，观察到了CO的形成，并且起始电势随着H 2 O浓度的变化而显着变化。考虑到CO谱带的Stark调谐速率（40 cm -1 / V），我们得出的结论是，CO的覆盖率很低，但是CO的存在会导致Pt表面失活并降低还原电流。