Bagger Alexander, Arnarson Logi, Hansen Martin H, Spohr Eckhard, Rossmeisl Jan
Department of Chemistry , University of Copenhagen , Universitetsparken 5 , 2100 Copenhagen , Denmark.
SUNCAT Center for Interface Science and Catalysis , SLAC National Accelerator Laboratory , Menlo Park , California 94025 , United States.
J Am Chem Soc. 2019 Jan 30;141(4):1506-1514. doi: 10.1021/jacs.8b08839. Epub 2019 Jan 22.
Electrochemical CO reduction holds the promise to be a cornerstone for sustainable production of fuels and chemicals. However, the underlying understanding of the carbon-carbon coupling toward multiple-carbon products is not complete. Here we present thermodynamically realistic structures of the electrochemical interfaces, determined by explicit ab initio simulations. We investigate how key CO reduction reaction intermediates are stabilized in different electrolytes and at different pH values. We find that the catalytic trends previously observed experimentally can be explained by the interplay between the metal surface and the electrolyte. For the Cu(100) facet with a phosphate buffer electrolyte, the energy efficiency is found to be limited by blocking of a phosphate anion, while in alkali hydroxide solutions (MOH, M = Na, K, Cs), OH* intermediates may be present, and at high overpotential the H* coverage limits the reaction. The results provide insight into the electrochemical interface structure, revealing the limitations for multiple-carbon products, and offer a direct comparison to experiments.
电化学CO还原有望成为可持续生产燃料和化学品的基石。然而，对于生成多碳产物的碳-碳偶联的基本理解并不完整。在此，我们展示了通过显式从头算模拟确定的电化学界面的热力学现实结构。我们研究了关键的CO还原反应中间体如何在不同电解质和不同pH值下得到稳定。我们发现，先前实验观察到的催化趋势可以通过金属表面与电解质之间的相互作用来解释。对于含有磷酸盐缓冲电解质的Cu(100)晶面，发现能量效率受到磷酸根阴离子的阻碍，而在碱金属氢氧化物溶液（MOH，M = Na、K、Cs）中，可能存在OH中间体，并且在高过电位下，H覆盖度限制了反应。这些结果深入了解了电化学界面结构，揭示了多碳产物的局限性，并与实验进行了直接比较。
