Confinement effects in CO2 electroreduction – mechanistic investigations on surfactant-tailored porous Cu electrodes

二氧化碳（CO2RR）的电化学转化为化学原料不仅提供了二氧化碳中性燃料循环的可能性，而且为工业所需的基础和价值化学品的可持续合成提供了途径。控制对多碳产物的选择性和抑制析氢仍然是CO2RR技术面临的主要科学挑战。铜作为CO2RR催化剂具有特殊的地位，因为它能够以显著的效率生成碳氢化合物和含氧化合物。在这里，我们利用定制的三维多孔Cu结构的约束效应来调节对多碳产物（C2+）的选择性。电极将采用易泡氢模板电沉积法制备，以建立多孔催化剂结构与其CO2RR活性之间的结构/性能关系。表面活性剂将用于定制孔径，尺寸分布和形态。催化剂中存在的密闭空间可以支持低反应中间体或产物与C2或更高的碳氢化合物/氧合物的C-C偶联，但这一点尚不充分了解。在操作条件下进行研究的适应性物理方法（Operando拉曼和x射线光谱和视频显微镜）以及电化学表征和CO2RR产物光谱的测定可能为理解空间限制对产物选择性的影响铺平道路，达到前所未有的水平。工作方案的关键内容是：1)利用气泡模板电沉积方法，通过合成参数和表面活性剂控制氢泡尺寸（气泡破裂直径），制备出新型的Cu催化剂的三维分层孔形态（微米孔）。2)建立微米孔和纳米孔区域的结构参数和定量形貌描述符。3)通过将定量形貌描述符与分析化学的产物谱相关联，确定孔隙度特征与产物谱之间的相关性。该项目结合了两个小组在电化学（合成和表征）和operando光谱研究方面的大量专业知识，以了解分层多孔双金属催化剂对CO2RR的选择性和活性的决定性因素。

The electrochemical conversion of CO2 (CO2RR) into chemical feedstocks does not only offer the possibility of a CO2-neutral fuel cycle, but also a sustainable synthesis route towards industrially required basic and value chemicals. Controlling the selectivity towards multi-carbon products and suppressing the hydrogen evolution remains one major scientific challenge in the CO2RR technology. Copper occupies a special position as a catalyst for CO2RR due to its ability to produce hydrocarbons and oxygenates with significant efficiency. Here, we exploit the confinement effect of tailored 3D porous Cu structures tuning the selectivity towards multi-carbon products (C2+). The electrodes will be fabricated by a facile hydrogen-bubble templated electrodeposition method to establish structure / property relations between the porous catalyst structure and their CO2RR activity. Surfactants will be utilized to tailor pore size, size distribution and morphology. The presence of confined spaces in the catalysts can support the C-C coupling of the lower reaction intermediates or products to C2 or higher hydrocarbons/oxygenates, but this is insufficiently understood. Adapted physical methods for investigation under operation conditions (Operando Raman & X-ray spectroscopy & video microscopy) together with electrochemical characterization and determination of the CO2RR product spectrum may pave the road towards understanding of the spatial confinement effect on product selectivity at an unprecedented level. The key elements of the work program are: 1) Exploit the bubble-templated electrodeposition approach to produce a new variety of 3D hierarchical pore morphologies (micrometer pores) of Cu catalysts by controlling the hydrogen bubble size (break-off diameter of the bubble) by means of synthesis parameters and surfactants. 2) Establish structure parameters and quantitative morphology descriptors for micrometer pores and nanoporous regions. 3) Identify correlations between porosity characteristics and product spectrum by relating quantitative morphology descriptors and the product spectrum from analytical chemistry. This project combines the substantial expertise of the two groups in electrochemical (synthesis & characterization) and operando spectroscopic investigation, to understand the factors decisive in the selectivity and activity of hierarchically porous bimetallic catalysts towards CO2RR.