Electrochemical Reduction of CO 2 : A Common Acetyl Path to Ethylene, Ethanol or Acetate

• Published in: Journal of the Electrochemical Society 2024-03, Vol.171 (3), p.34501
• Main Authors: Dauda, Monsuru, Hendershot, John, Bello, Mustapha, Park, Junghyun, Loaiza Orduz, Alvaro, Lombardo, Nicholas, Kizilkaya, Orhan, Sprunger, Phillip, Engler, Anthony, Plaisance, Craig, Flake, John
• Format: Article
• Language: English
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/1945-7111/ad2cc1

Ethylene is well known as the primary product of CO 2 reduction at Cu electrocatalysts using zero-gap membrane electrode assembly cells with gas diffusion cathodes. Other types of Cu electrocatalysts including oxide-derived Cu, CuSn and CuSe yield relatively more C 2 oxygenates; however, the mechanisms for C 2 product selectivity are not well established. This work considers selectivity trends of Cu-P 0.065 , Cu-Sn 0.03 , and Cu 2 Se electrocatalysts made using a standard one pot synthesis method. Results show that Cu-P 0.065 electrocatalysts (Cu δ + = 0.13) retain ethylene as a primary product with relatively higher Faradaic efficiencies (FE = 43% at 350 mA cm −2 ) than undoped Cu electrocatalysts (FE = 31% at 350 mA cm −2 ) at the same current density. The primary CO 2 reduction product at Cu-Sn 0.03 (Cu δ + = 0.27) electrocatalysts shifts to ethanol (FE = 48% at 350 mA cm −2 ) while CO 2 reduction at Cu 2 Se (Cu δ + = 0.47) electrocatalysts favor acetate production (FE = 40% at 350 mA cm −2 ). Based on these results, we propose a common acetyl intermediate and a mechanism for selective formation of ethylene, ethanol or acetate based on the degree of partial positive charge ( δ + ) of Cu reaction sites.