Facet-switching of rate-determining step on copper in CO2-to-ethylene electroreduction

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 121; no. 25; p. 1
• Main Authors: Zhang, Yu-Cai, Zhang, Xiao-Long, Wu, Zhi-Zheng, Niu, Zhuang-Zhuang, Chi, Li-Ping, Gao, Fei-Yue, Yang, Peng-Peng, Wang, Ye-Hua, Yu, Peng-Cheng, Duanmu, Jing-Wen, Sun, Shu-Ping, Gao, Min-Rui
• Format: Journal Article
• Language: English
• Published: Washington National Academy of Sciences 18.06.2024
• Subjects: Carbon dioxide; Catalysts; Copper; Efficiency; Electrodes; Electrowinning; Energy efficiency; Ethylene; Physical Sciences; Protonation
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.2400546121

Reduction of carbon dioxide (CO2) by renewable electricity to produce multicarbon chemicals, such as ethylene (C2H4), continues to be a challenge because of insufficient Faradaic efficiency, low production rates, and complex mechanistic pathways. Here, we report that the rate-determining steps (RDS) on common copper (Cu) surfaces diverge in CO2 electroreduction, leading to distinct catalytic performances. Through a combination of experimental and computational studies, we reveal that C─C bond-making is the RDS on Cu(100), whereas the protonation of *CO with adsorbed water becomes rate-limiting on Cu(111) with a higher energy barrier. On an oxide-derived Cu(100)-dominant Cu catalyst, we reach a high C2H4 Faradaic efficiency of 72%, partial current density of 359 mA cm−2, and long-term stability exceeding 100 h at 500 mA cm−2, greatly outperforming its Cu(111)-rich counterpart. We further demonstrate constant C2H4 selectivity of >60% over 70 h in a membrane electrode assembly electrolyzer with a full-cell energy efficiency of 23.4%.