Data underlying the publication: Non-invasive current collectors for improved current-density distribution during CO2 electrolysis on super-hydrophobic electrodes

Electrochemical reduction of CO2 presents an attractive way to store renew- able energy in chemical bonds in a potentially carbon-neutral way. However, the available electrolyzers suffer from intrinsic problems, like flooding and salt accumulation, that must be overcome to industrialize the technology. To mitigate flooding and salt precipitation issues, researchers have used super- hydrophobic electrodes based on either expanded polytetrafluoroethylene (ePTFE) gas-diffusion layers (GDL’s), or carbon-based GDL’s with added PTFE. While the PTFE backbone is highly resistant to flooding, the non-conductive nature of PTFE means that without additional current collection the catalyst layer itself is responsible for electron-dispersion, which penalizes system efficiency and stability. In this work, we present operando results that illustrate that the current distribution and electrical potential distribution is far from a uniform distribution in thin catalyst layers (~50 nm) deposited onto ePTFE GDL’s. We then compare the effects of thicker catalyst layers (~500 nm) and a newly developed non-invasive current collector (NICC). The NICC can main- tain more uniform current distributions with 10-fold thinner catalyst layers while improving stability towards ethylene (≥ 30%) by approximately two-fold.

二氧化碳电化学还原是一种极具潜力的技术，可将可再生能源以化学键的形式储存，且有望实现近乎碳中和的目标。然而，当前已有的电解槽存在水淹、盐积等固有问题，若要实现该技术的工业化应用，必须攻克这些难题。为缓解水淹与盐析问题，研究人员已开发出两类超疏水电极：一类基于膨体聚四氟乙烯（expanded polytetrafluoroethylene, ePTFE）气体扩散层（gas-diffusion layer, GDL），另一类基于添加聚四氟乙烯（PTFE）的碳基气体扩散层。尽管聚四氟乙烯（PTFE）骨架具备优异的抗水淹性能，但其非导电特性意味着，若缺乏额外的集流结构，催化剂层需独自承担电子分散的功能，这会显著降低系统的效率与稳定性。本研究通过原位（operando）表征结果证实：沉积于膨体聚四氟乙烯气体扩散层上的薄层催化剂（厚度约50 nm）中，电流分布与电位分布均远非均匀分布。随后，我们对比了厚层催化剂（厚度约500 nm）与新型非侵入式集流器（non-invasive current collector, NICC）的应用效果。该非侵入式集流器（NICC）可在催化剂层厚度仅为原有1/10的条件下维持更均匀的电流分布，同时将乙烯生成方向的稳定性提升约两倍，且乙烯产物占比不低于30%。