Selective Electrochemical CO <sub>2</sub> Reduction to Ethylene or Ethanol via Tuning *OH Adsorption
Dazhong Zhong, Qiang Fang, Runxin Du, Yaxin Jin, Peng Chen, Dongfang Cheng, Tan Li, Tao Zhao, Sheng Zhang, Yao Zheng, Qiang Zhao, Qiang Zhao, Yuhan Sun, Yuhan Sun, Jinping Li
Abstract
Abstract Selective electrocatalytic reduction of carbon dioxide (CO 2 RR) into ethylene (C 2 H 4 ) or ethanol (C 2 H 5 OH) is a high challenge. In this study, the rational manipulation of Cu defect sites was realized for the selective formation of C 2 H 5 OH and C 2 H 4 . Low‐coordination amorphous and medium‐coordination grain‐boundary Cu defect sites with different *OH affinity were found to play a decisive role in the selective protonation of CH 2 CHO*. In particular, grain‐boundary‐rich Cu (denoted as Cu‐1) that weakly adsorbed *OH and CH 2 CHO* favored the protonation on β‐C of CH 2 CHO*, leading to the selective production of C 2 H 5 OH. In contrast, amorphous Cu defect sites (denoted as Cu‐3) showed strong *OH adsorption and then strong CH 2 CHO* adsorption, facilitating C−O breaking and C 2 H 4 formation. In the membrane electrode assembly (MEA) configuration, a remarkably high full‐cell energy efficiency (EE) of 29.0 % for C 2 H 5 OH on Cu‐1 and an impressive high full‐cell EE of 25.6 % for C 2 H 4 on Cu‐3 were observed. In addition, a C 2 H 4 Faradaic efficiency (FE) of 63.4±1.5 % was achieved on Cu‐3 at a notable current of 12.5 A with a 25 cm −2 MEA configuration. These results provided crucial insights into the significance of defect sites in manipulating the adsorption of *OH for the selective production of C 2 H 4 or C 2 H 5 OH.