Center for Catalytic Science and Technology, Department of Chemical and Biomolecular Engineering, University of Delaware , Newark, Delaware 19716, United States.
Department of Chemical Engineering, Columbia University , New York, New York 10027, United States.
J Am Chem Soc. 2017 Mar 15;139(10):3774-3783. doi: 10.1021/jacs.6b13287. Epub 2017 Mar 6.
Much effort has been devoted in the development of efficient catalysts for electrochemical reduction of CO. Molecular level understanding of electrode-mediated process, particularly the role of bicarbonate in increasing CO reduction rates, is still lacking due to the difficulty of directly probing the electrochemical interface. We developed a protocol to observe normally invisible reaction intermediates with a surface enhanced spectroscopy by applying square-wave potential profiles. Further, we demonstrate that bicarbonate, through equilibrium exchange with dissolved CO, rather than the supplied CO, is the primary source of carbon in the CO formed at the Au electrode by a combination of in situ spectroscopic, isotopic labeling, and mass spectroscopic investigations. We propose that bicarbonate enhances the rate of CO production on Au by increasing the effective concentration of dissolved CO near the electrode surface through rapid equilibrium between bicarbonate and dissolved CO.
在开发用于电化学还原 CO 的高效催化剂方面已经做了很多努力。由于直接探测电化学界面具有挑战性，因此对于电极介导的过程（特别是碳酸氢根在提高 CO 还原速率方面的作用），在分子水平上的理解仍然缺乏。我们开发了一种通过施加方波电势曲线用表面增强光谱法来观察通常不可见的反应中间体的方案。此外，我们通过原位光谱、同位素标记和质谱研究证明，碳酸氢根通过与溶解的 CO 进行平衡交换，而不是供应的 CO，是 Au 电极上形成的 CO 中碳的主要来源。我们提出，碳酸氢根通过在碳酸氢根和溶解的 CO 之间的快速平衡，增加了电极表面附近溶解的 CO 的有效浓度，从而提高了 Au 上 CO 生成的速率。
