Constraining CO<sub>2</sub> Coverage on Copper Promotes CO<sub>2</sub> Electroreduction to Multi‐carbon Products in Strong Acid
Wanfeng Yang, Yong Zhao, Yiqing Chen, Hangjuan Ren, Jiameng Sun, Zhangsheng Shi, Xindie Jin, Zhonghua Zhang, Zhonghua Zhang, Xin Wang
Abstract
Abstract Electrocatalytic CO 2 reduction (CO 2 R) to multi‐carbon (C 2+ ) products in strong acid presents a promising approach to mitigate the CO 2 loss commonly encountered in alkaline and neutral systems. However, this process often suffers from low selectivity for C 2+ products due to the competing C 1 (e.g., CO and HCOOH) formation and complex C−C coupling kinetics. In this work, we report a CO 2 coverage constraining strategy by diluting CO 2 reactant feed to modulate the intermediate distribution and C−C coupling pathways for an enhanced electrosynthesis of C 2+ products in strong acid. Lowering the CO 2 feed concentration reduces CO 2 coverage on copper catalyst, enriching the surface coverage and optimizing the adsorption configuration of the key CO intermediate for C−C coupling. This approach efficiently suppresses the formation of undesired C 1 products. By employing a 20 % CO 2 feed, we achieved a significant improvement in C 2+ Faradaic efficiency, reaching 68 % at 100 mA cm −2 , approximately 1.7 times higher than the 41 % obtained using pure CO 2 . We demonstrated the direct electroreduction of a 30 % CO 2 feed—representative CO 2 concentration of typical industrial flue gases—in a full electrolyzer, achieving a C 2+ selectivity of 78 % and an energy efficiency of 23 % at 200 mA cm −2 .