The electrochemical production of ethylene oxide (EO) from CO₂, water and renewable electricity could result in a net consumption of CO₂. Unfortunately existing electrochemical CO₂-to-EO conversions show impractical Faradaic efficiency (FE) and require a high energy input. Here we report a class of period-6-metal-oxide-modified iridium oxide catalysts that enable us to achieve improved CO₂-to-EO conversion. Among barium, lanthanum, cerium and bismuth, we find that barium-oxide-loaded catalysts achieve an ethylene-to-EO FE of 90%. When we pair this with the oxygen reduction reaction at the cathode, we achieve an energy input of 5.3 MJ per kg of EO, comparable to that of existing (emissions-intensive) industrial processes. We have also devised a redox-mediated paired system that shows a 1.5-fold higher CO₂-to-EO FE (35%) and uses a 1.2 V lower operating voltage than literature benchmark electrochemical systems.

_{从 CO 2} 、水和可再生电力电化学生产环氧乙烷 (EO)可能导致 CO ₂的净消耗。不幸的是，现有的电化学 CO ₂到 EO 的转化显示出不切实际的法拉第效率 (FE) 并且需要高能量输入。在这里，我们报告了一类周期 6 金属氧化物改性的氧化铱催化剂，使我们能够实现改进的 CO ₂-to-EO 转换。在钡、镧、铈和铋中，我们发现负载氧化钡的催化剂实现了 90% 的乙烯-EO FE。当我们将其与阴极的氧还原反应配对时，我们实现了每公斤 EO 5.3 MJ 的能量输入，与现有（排放密集型）工业过程的能量输入相当。我们还设计了一种氧化还原介导的配对系统，该系统显示出比文献基准电化学系统高 1.5 倍的 CO ₂ -to-EO FE (35%) 并使用低 1.2 V 的工作电压。