Yuqing Hou, Pengsong Li, Yong Wang, Xiangda Zhang, Shuaiqiang Jia, Jiahao Yang, Ganwen Zhang, Yichao Zhang, Xihua Wang, Rongjuan Feng, Xinchen Kang, Xiaofu Sun, Lihong Jing, Qingli Qian, Jianling Zhang, Qinggong Zhu, Buxing Han
Electroreduction of CO 2 to multicarbon (C 2+ ) alcohols in an acidic electrolyte presents a promising route for efficient carbon utilization. However, achieving high selectivity with high current density remains a major challenge due to multiple competing reactions in an acidic electrolyte. Herein, we develop a Ca species-templated strategy to construct bicrystalline Cu architectures (dCu(OH) 2 /Ca x ) for the selective conversion of CO 2 to C 2+ alcohols in acid. At a high current density of 700 mA cm –2, the C 2+ product faradaic efficiency (FE) could reach 81.2%, of which the FE of C 2+ alcohols was 51.6% with a partial current density of 361.4 mA cm –2, which is higher than those reported in acidic electrolytes. The C 2+ alcohol/C 2 H 4 ratio was as high as 1.9, compared with the 0.48 observed for the dCu(OH) 2 electrode. Mechanistic studies reveal that Ca species act as templates, directing the formation of 3D dendritic bicrystalline Cu structures rich in Cu (111)/(200) interfaces. These interfaces significantly enhance the adsorption of hydroxyl groups (*OH ad ) in an acidic electrolyte, which plays a dual role in promoting the conversion of CO 2 to C 2+ alcohols in acid. The *OH ad -functionalized Cu (111)/(200) interfaces not only suppress the hydrogen evolution reaction by altering the hydrogen-bonding network of interfacial water but also stabilize the key *CHCOH intermediate, facilitating its hydrogenation to *CHCH x OH for the generation of C 2+ alcohols. This synergistic interplay between the catalyst structure and interfacial chemistry enables efficient and selective production of C 2+ alcohols in acidic environments.