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Redox-mediated electrosynthesis of ethylene oxide from CO2 and water


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.

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Fig. 1: Comparison of BaOx/IrO2 and bare IrO2 electrocatalysts.
Fig. 2: Characterization of BaOx/IrO2 electrocatalysts.
Fig. 3: Electrochemical performance of BaOx/IrO2 electrocatalysts.
Fig. 4: Coupling with cathodic ORR and redox-mediated paired system.

Data availability

The data supporting the findings of this study are available within the paper, the Supplementary Information and the source data files. Source data are provided with this paper.


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This work was supported by the National Research Council Materials for Clean Fuels program (MCF-109), the Ontario Ministry of Colleges and Universities (grant ORF-RE08-034) and the Natural Sciences and Engineering Research Council (NSERC) of Canada (grant RGPIN-2017-06477). We thank P. Karimi, X. Wang, Y. C. Li, J. P. Edwards and C. P. O’Brien for discussions. Y. Li acknowledges financial support from the China Scholarship Council (201906745001). W.R.L. acknowledges financial support from an A*STAR Young Individual Research Grant (grant number A2084c0180).

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Authors and Affiliations



C.L. and E.H.S. supervised the project. Y. Li, A.O. and W.R.L. conceived the idea and designed and carried out the experiments. Y. Li and W.R.L. collected STEM and TEM images and carried out energy-dispersive X-ray spectroscopy mapping. P.O. carried out theoretical calculations. Y.X. fabricated the customized flow cell. Y. Liu and K.B. performed X-ray diffraction and XPS measurements. A.O. carried out analysis of CO2RR products. Y. Li and W.R.L. analysed ethylene chlorohydrin and EO products. J.E.H., Y.W., C.R., H.J. and D.S. contributed to data analysis and manuscript editing. Y. Li, C.L. and E.H.S. co-wrote the paper. All authors discussed the results and assisted during manuscript preparation.

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Correspondence to Chunzhong Li or Edward H. Sargent.

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Competing interests

Y. Li, A.O., W.R.L, P.O. and E.H.S. have filed provisional patent application number 63/265.897 regarding the electrosynthesis of oxiranes. The other authors declare no competing interests.

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Nature Catalysis thanks the anonymous reviewers for their contribution to the peer review of this work.

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Supplementary Information

Supplementary Figs. 1–20, Tables 1–9, equations (1)–(18), notes 1–4 and references.

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Li, Y., Ozden, A., Leow, W.R. et al. Redox-mediated electrosynthesis of ethylene oxide from CO2 and water. Nat Catal 5, 185–192 (2022).

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