Hamilton Sara T, Kelly Maria, Smith Wilson A, Park Ah-Hyung Alissa
Department of Earth and Environmental Engineering, Columbia University, New York, New York 10027, United States.
National Renewable Energy Laboratory, Golden, Colorado 80401, United States.
ACS Appl Mater Interfaces. 2024 Aug 14;16(32):42021-42033. doi: 10.1021/acsami.4c01908. Epub 2024 Aug 1.
Integrating CO capture and electrochemical conversion has been proposed as a strategy to reduce the net energy required for CO regeneration in traditional CO capture and conversion schemes and can be coupled with carbon-free renewable electricity. Polyethylenimine (PEI)-based materials have been previously studied as CO capture materials and can be integrated in these reactive capture processes. PEI-based electrolytes have been found to significantly increase the CO loading, and impact selectivity and rate of product formation when compared to the conventional aqueous electrolytes. However, the influence of these materials at the catalyst-electrode interface is currently not well understood. In this study, PEI-based electrolytes were prepared and their impact on the morphology of a silver electrode performing electrochemical CO reduction (COR) was studied using in situ electrochemical atomic force microscopy (EC-AFM). The presence of PEI on the electrode surface could be distinguished based on nanomechanical properties (DMT modulus), and changes were observed as negative polarization was applied, revealing a reorganization of the PEI chains due to electrostatic interactions. These changes were impacted by the electrolyte composition, including the addition of supporting electrolyte KHCO salt, as well as CO captured by the PEI-based electrolyte, which minimized the change in surface mechanical properties and degree of PEI alignment on the electrode surface. The changes in surface mechanical properties were also dependent on the PEI polymer length, with higher molecular weight PEI showing different reconfiguration than the shorter polymer brushes. The study highlights that the choice of polymer material, the electrolyte composition, and CO captured impact the near-electrode environment, which has implications for COR, and presents EC-AFM as a new tool that can be used to probe the dynamic behavior of these interfaces during electrocatalysis.
将二氧化碳捕集与电化学转化相结合，已被提议作为一种策略，以减少传统二氧化碳捕集与转化方案中二氧化碳再生所需的净能量，并且可以与无碳可再生电力相结合。基于聚乙烯亚胺（PEI）的材料此前已作为二氧化碳捕集材料进行过研究，并且可以集成到这些反应性捕集过程中。已发现基于PEI的电解质可显著提高二氧化碳负载量，并且与传统水性电解质相比，会影响产物形成的选择性和速率。然而，目前对这些材料在催化剂-电极界面处的影响尚不清楚。在本研究中，制备了基于PEI的电解质，并使用原位电化学原子力显微镜（EC-AFM）研究了它们对进行电化学二氧化碳还原（COR）的银电极形态的影响。基于纳米力学性能（DMT模量）可以区分电极表面上PEI的存在，并且在施加负极化时观察到了变化，这表明由于静电相互作用，PEI链发生了重新排列。这些变化受到电解质组成的影响，包括添加支持电解质KHCO盐，以及基于PEI的电解质捕获的二氧化碳，这使表面机械性能的变化以及电极表面上PEI排列的程度最小化。表面机械性能的变化还取决于PEI聚合物的长度，较高分子量的PEI与较短的聚合物刷相比表现出不同的重新构型。该研究强调，聚合物材料的选择、电解质组成和捕获的二氧化碳会影响近电极环境，这对COR有影响，并将EC-AFM作为一种新工具展示出来，可用于探测电催化过程中这些界面的动态行为。
