Electrochemical CO₂ reduction is a typical surface-mediated reaction, with its reaction kinetics and product distributions largely dependent on the dynamic evolution of reactive species at the cathode–catholyte interface and on the resultant mass transport within the hydrodynamic boundary layer in the vicinity of the cathode. To resolve the complex local reaction environment of branching CO₂ reduction pathways, we here present a differential electrochemical mass spectroscopic (DEMS) approach for Cu electrodes to investigate CO₂ mass transport, the local concentration gradients of buffering anions, and the Cu surface topology effects on CO₂ electrolysis selectivity at a temporal resolution of ∼400 ​ms. As a proof of concept, these tuning knobs were validated on an anion exchange membrane electrolyzer, which delivered a Faradaic efficiency of up to 40.4% and a partial current density of 121 ​mA ​cm⁻² for CO₂-to-C₂H₄ valorization. This methodology, which bridges the study of fundamental surface electrochemistry and the upgrading of practical electrolyzer performance, could be of general interest in helping to achieve a sustainable circular carbon economy.

电化学CO ₂还原是一种典型的表面介导反应，其反应动力学和产物分布在很大程度上取决于阴极-阴极电解液界面上活性物质的动态演化以及由此产生的在阴极附近的流体动力学边界层内的传质。阴极。为了解决分支CO ₂还原途径的复杂局部反应环境，我们在此提出了一种用于Cu电极的微分电化学质谱（DEMS）方法，以研究CO ₂传质、缓冲阴离子的局部浓度梯度和Cu表面拓扑效应二氧化碳₂时间分辨率约为 400 毫秒的电解选择性。作为概念证明，这些调谐旋钮在阴离子交换膜电解槽上进行了验证，其法拉第效率高达 40.4%，CO 2 -to-C 2 H 的部分电流密度_为121 _mA cm ^-2 ₄增值。这种方法将基础表面电化学的研究和实际电解槽性能的升级联系起来，在帮助实现可持续的循环碳经济方面可能会引起普遍的兴趣。