Efficient electrically powered CO2-to-ethanol via suppression of deoxygenation

• Published in: Nature energy 2020-06, Vol.5 (6), p.478-486
• Main Authors: Wang, Xue, Wang, Ziyun, García de Arquer, F. Pelayo, Dinh, Cao-Thang, Ozden, Adnan, Li, Yuguang C., Nam, Dae-Hyun, Li, Jun, Liu, Yi-Sheng, Wicks, Joshua, Chen, Zitao, Chi, Miaofang, Chen, Bin, Wang, Ying, Tam, Jason, Howe, Jane Y., Proppe, Andrew, Todorović, Petar, Li, Fengwang, Zhuang, Tao-Tao, Gabardo, Christine M., Kirmani, Ahmad R., McCallum, Christopher, Hung, Sung-Fu, Lum, Yanwei, Luo, Mingchuan, Min, Yimeng, Xu, Aoni, O’Brien, Colin P., Stephen, Bello, Sun, Bin, Ip, Alexander H., Richter, Lee J., Kelley, Shana O., Sinton, David, Sargent, Edward H.
• Format: Article
• Language: English
• Subjects: 639/4077/4057; 639/4077/909/4101/4102; 639/638/161/886; Carbon dioxide; Catalysts; Confinement; Copper; Deoxygenation; Economics and Management; Efficiency; Electrocatalysts; Electrowinning; Energy; Energy efficiency; Energy Policy; Energy Storage; Energy Systems; Ethanol; Nitrogen; Renewable and Green Energy; Renewable energy; Spectroscopy
• ISSN: 2058-7546; 2058-7546
• DOI: 10.1038/s41560-020-0607-8

The carbon dioxide electroreduction reaction (CO 2 RR) provides ways to produce ethanol but its Faradaic efficiency could be further improved, especially in CO 2 RR studies reported at a total current density exceeding 10 mA cm −2 . Here we report a class of catalysts that achieve an ethanol Faradaic efficiency of (52 ± 1)% and an ethanol cathodic energy efficiency of 31%. We exploit the fact that suppression of the deoxygenation of the intermediate HOCCH* to ethylene promotes ethanol production, and hence that confinement using capping layers having strong electron-donating ability on active catalysts promotes C–C coupling and increases the reaction energy of HOCCH* deoxygenation. Thus, we have developed an electrocatalyst with confined reaction volume by coating Cu catalysts with nitrogen-doped carbon. Spectroscopy suggests that the strong electron-donating ability and confinement of the nitrogen-doped carbon layers leads to the observed pronounced selectivity towards ethanol. The electroreduction of CO 2 to ethanol could enable the clean production of fuels using renewable power. This study shows how confinement effects from nitrogen-doped carbon layers on copper catalysts enable selective ethanol production from CO 2 with a Faradaic efficiency of up to 52%.