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

将CO2（CO2 RR）电化学转化为化学原料不仅提供了CO2中性燃料循环的可能性，而且还提供了工业所需的基本和有价值化学品的可持续合成路线。控制对多碳产物的选择性和抑制析氢仍然是CO2 RR技术中的一个主要科学挑战。铜作为CO2 RR的催化剂占据特殊地位，因为它能够以显著的效率生产烃和含氧化合物。在这里，我们利用定制的3D多孔Cu结构的限制效应来调整对多碳产物（C2+）的选择性。电极将通过简易的氢气泡模板电沉积方法制造，以建立多孔催化剂结构与其CO2 RR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。催化剂中有限空间的存在可以支持低级反应中间体或产物与C2或更高级烃/含氧化合物的C-C偶联，但这还没有充分理解。在操作条件下（Operando拉曼和X-射线光谱和视频显微镜）的调查适应物理方法与电化学表征和CO2 RR产品光谱的测定可能铺平道路，以前所未有的水平对产品选择性的空间限制效应的理解。工作方案的主要内容是：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气泡尺寸（气泡的破裂直径），制备各种新的Cu催化剂的3D分级孔形态（微米孔）。（二） 建立微米孔和纳米孔区域的结构参数和定量形态描述符。第三章 通过将定量形态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）和操作光谱研究方面的大量专业知识，以了解分层多孔催化剂对CO2 RR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.