Ren Dan, Gao Jing, Zakeeruddin Shaik M, Grätzel Michael
Laboratory of Photonics and Interfaces, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
J Phys Chem Lett. 2021 Aug 12;12(31):7583-7589. doi: 10.1021/acs.jpclett.1c02043. Epub 2021 Aug 4.
The implementation of an electrochemical flow cell has enabled improved efficiency for CO reduction. However, spectroscopic insights into the interface are still lacking. Here, we investigate a series of copper layers with different thicknesses on gas diffusion electrodes as a benchmark, with the best-performing one showing a Faradaic efficiency of 59.5% and a partial current density of -170 mA cm for ethylene formation in 1 M KOH at -0.70 V against a reversible hydrogen electrode. By comparing the geometric as well as specific current density for ethylene on four Cu catalysts with different thicknesses, we illustrate the effects of bulk pH, local pH, and diffusion of CO on C-C coupling. We also reveal that the flexible rotation of the Cu-C bond of the *CO intermediate adsorbed on Cu, as shown by Raman spectroscopy, is likely to be the key factor for efficient C-C coupling in a flow cell.
电化学流通池的应用提高了CO还原效率。然而，对于界面的光谱洞察仍然不足。在此，我们研究了气体扩散电极上一系列不同厚度的铜层作为基准，其中性能最佳的铜层在相对于可逆氢电极-0.70 V的1 M KOH中，乙烯生成的法拉第效率为59.5%，部分电流密度为-170 mA cm²。通过比较四种不同厚度的Cu催化剂上乙烯的几何电流密度和比电流密度，我们阐述了本体pH值、局部pH值和CO扩散对C-C偶联的影响。我们还发现，如拉曼光谱所示，吸附在Cu上的*CO中间体的Cu-C键的灵活旋转可能是流通池中高效C-C偶联的关键因素。
