Anolyte Buffering and CO Coverage Effects in the Electrochemical Reduction of CO at Cu Electrocatalysts

Authors

• Mustapha Bello, Cain Department of Chemical Engineering
• Monsuru Olatunji Dauda, Cain Department of Chemical Engineering
• John Hendershot, Cain Department of Chemical Engineering
• Nkechi Kingsley, Cain Department of Chemical Engineering
• Ignace Agbadan, Cain Department of Chemical Engineering
• Junghyun Park, Cain Department of Chemical Engineering
• Soundarzo Tasnim, Cain Department of Chemical Engineering

Document Type

Article

Publication Date

10-13-2025

Abstract

Electrolytic CO reduction was investigated at copper electrocatalysts in zero-gap membrane electrode assemblies as a function of buffering agents and cofeeding with CO2or Ar. Results show an acetate Faradaic efficiency (FE) of 90% at 300 mA cm^–2using pure CO feeds and phosphate-buffered anolyte near pH 8. When using CO feeds with more alkaline anolytes, the hydrogen evolution reaction becomes the dominant reduction reaction, independent of the buffer. Product distributions of cofeeding experiments with CO and CO2show that increasing CO2cofeeding results in increased selectivity toward ethylene (42% FE) in near-neutral KHCO3anolytes or ethanol (40% FE) in alkaline KOH anolytes. Evaluation of several commercial anion exchange membranes shows similar selectivity trends, suggesting product selectivity is dominated by the local pH and surface coverage of CO. Based on these results, we propose pH buffering and CO coverage behaviors that facilitate high selectivities to acetate.

Publication Source (Journal or Book title)

ACS Applied Energy Materials

First Page

14299

Last Page

14306

Recommended Citation

Bello, M., Dauda, M., Hendershot, J., Kingsley, N., Agbadan, I., Park, J., & Tasnim, S. (2025). Anolyte Buffering and CO Coverage Effects in the Electrochemical Reduction of CO at Cu Electrocatalysts. ACS Applied Energy Materials, 8 (19), 14299-14306. https://doi.org/10.1021/acsaem.5c01865