Oxygen-tolerant Electrochemical CO2 Reduction from Bicarbonate Solutions toward Multicarbon Compounds (Supporting Information)

Electrochemical CO2 reduction to multicarbon products offers a promising pathway for closing the anthropogenic carbon cycle while producing value-added chemicals. However, conventional gaseous CO2 electrolysis suffers from severe performance losses when O2 impurities are present. In this study, we focused on a HCO3−-derived CO2 reduction system, in which gaseous CO2 is generated in-situ within the electrolyzer, enabling efficient formation of a three-phase interface required for high-rate C2+ synthesis. We have successfully achieved a faradaic efficiency of 67.4 % and a partial current density exceeding 300 mA cm−2 for C2+ compounds. Importantly, the HCO3−-derived CO2RR demonstrated excellent oxygen tolerance, maintaining both the faradaic efficiency and partial current density for C2+ products even when CO2 gas containing 20 % O2 was used as the source for HCO3− solutions.

将二氧化碳电化学还原为多碳产物，是在制备高附加值化学品的同时闭合人为碳循环的极具前景的路径。然而，传统气态二氧化碳电解体系在存在氧气杂质时会出现严重的性能衰减。本研究聚焦于碳酸氢根（HCO3−）衍生的二氧化碳还原体系，该体系可在电解槽内原位生成气态二氧化碳，从而高效构建高速率C2+合成所需的三相界面。本研究成功实现了C2+产物67.4%的法拉第效率（Faradaic efficiency），以及超过300 mA cm−2的偏电流密度（partial current density）。值得注意的是，该碳酸氢根衍生的二氧化碳还原反应（CO2RR）展现出优异的耐氧性能：即便使用含20%氧气的二氧化碳气体作为碳酸氢根溶液的原料气，其C2+产物的法拉第效率与偏电流密度仍能保持稳定。