Electrochemical carbon dioxide (CO) reduction reaction (CORR) has long been known to be affected by the electrolyte cations, yet the interpretations of these effects remain controversial. In this work, taking advantage of the unique catalytic characteristics of Pd, we investigated the cation effects on the CORR. It was found that the productions of formate and carbon monoxide (CO) are accelerated, and the competitive hydrogen evolution reaction (HER) is suppressed on Pd surfaces by larger cations. Detailed ATR-SEIRAS measurements revealed the promotion of CORR comes from two aspects. First, the CO molecules can be concentrated at the electrode–electrolyte interface by larger cations through electrostatic interaction. Second, a stronger interfacial electric field brought by the larger cations can accelerate the CORR and stabilize the negatively charged intermediates. The potential-dependent spectral transitions of adsorbed CO and interfacial water shed new light on the cation-dependent electric double layer structures. In light of these findings, the cation effects on the formate and CO pathways at different overpotentials were further revealed.

中文翻译：

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揭示阳离子对 Pd/C 催化剂上 CO2 电还原的影响——SEIRAS 研究


人们早就知道电化学二氧化碳（CO）还原反应（CORR）会受到电解质阳离子的影响，但对这些影响的解释仍然存在争议。在这项工作中，我们利用 Pd 独特的催化特性，研究了阳离子对 CO2RR 的影响。研究发现，较大的阳离子会加速甲酸盐和一氧化碳 (CO) 的产生，并且抑制 Pd 表面的竞争性析氢反应 (HER)。详细的 ATR-SEIRAS 测量揭示了 CORR 的促进来自两个方面。首先，CO分子可以通过静电相互作用通过较大的阳离子聚集在电极-电解质界面。其次，较大的阳离子带来的更强的界面电场可以加速CO2RR并稳定带负电的中间体。吸附的 CO 和界面水的电势依赖性光谱跃迁为阳离子依赖性双电层结构提供了新的线索。根据这些发现，进一步揭示了不同过电势下阳离子对甲酸盐和 CO 途径的影响。