Li Zhuofeng, Wang Linqin, Sun Licheng, Yang Wenxing
Center of Artificial Photosynthesis for Solar Fuels and Department of Chemistry, School of Science and Research Center for Industries of the Future, Westlake University, 600 Dunyu Road, Hangzhou 310030, Zhejiang, China.
Institute of Natural Sciences, Westlake Institute for Advanced Study, 18 Shilongshan Road, Hangzhou 310024, Zhejiang, China.
J Am Chem Soc. 2024 Aug 28;146(34):23901-23908. doi: 10.1021/jacs.4c06404. Epub 2024 Jul 26.
Recently, pulsed electrolysis has been demonstrated as an emerging electrochemical technique that significantly promotes the performance of various electrocatalysis applications. The ionic nature of aqueous electrolytes implies a likely change in ionic distribution under these alternating potential conditions. However, despite the well-known importance of cations, the impact of pulsed electrolysis on the cation distribution remains unexplored as well as its influences on the performance. Herein, we explore the cation effects on the pulsed electrochemical CO reduction (p-CORR) using the most widely utilized alkali metal cations, including Li, Na, K, and Cs. It is discovered that the nature of cations can significantly influence the product ratio of C over C (mostly CH) during p-CORR in an order of Li< Na< K< Cs, much more profoundly than those of static cases. We report direct experimental evidence for the cation enrichment caused by pulsed electrolysis, depending on the radius of the hydrated ions. With further quasi-in situ analysis of the catalyst surface, the cation-promoted Cu dissolution-and-redeposition process was identified; this is found to alter the surface CuO/Cu ratio during the pulsed process. We demonstrate that both the cation enrichment and the cation-adjusted surface CuO/Cu composition impact the C/C ratio through the control of the surface-adsorbed CO population. These results reveal the presence of pulse-induced cation redistribution in emerging pulsed electrolysis techniques and provide a comprehensive understanding of alkali metal cation effects for improving the selectivity of p-CORR.
最近，脉冲电解已被证明是一种新兴的电化学技术，可显著提升各种电催化应用的性能。水性电解质的离子性质意味着在这些交变电位条件下离子分布可能会发生变化。然而，尽管阳离子的重要性众所周知，但脉冲电解对阳离子分布的影响及其对性能的影响仍未得到探索。在此，我们使用最广泛使用的碱金属阳离子（包括锂、钠、钾和铯）来探索阳离子对脉冲电化学CO还原（p-CORR）的影响。研究发现，在p-CORR过程中，阳离子的性质可显著影响C与C（主要是CH）的产物比例，顺序为Li<Na<K<Cs，其影响程度比静态情况更为显著。我们报告了脉冲电解导致阳离子富集的直接实验证据，这取决于水合离子的半径。通过对催化剂表面的进一步准原位分析，确定了阳离子促进的铜溶解和再沉积过程；发现在脉冲过程中这会改变表面CuO/Cu比例。我们证明，阳离子富集和阳离子调节的表面CuO/Cu组成均通过控制表面吸附的CO数量来影响C/C比例。这些结果揭示了新兴脉冲电解技术中存在脉冲诱导的阳离子重新分布，并为理解碱金属阳离子对提高p-CORR选择性的影响提供了全面认识。
