Localized Geometry Determined Selectivity of Iodide‐Derived Copper for Electrochemical CO<sub>2</sub> Reduction
Yuchuan Shi, Yiqing Wang, Chung‐Li Dong, Ta Thi Thuy Nga, Daixing Wei, Jialin Wang, Xiaoli Zhao, Miao Wang, Kaini Zhang, Mingtao Li, Fan Dong, Shaohua Shen
Abstract
Abstract Two iodide‐derived copper (ID‐Cu) electrocatalysts (E‐ID‐Cu and W‐ID‐Cu) are prepared by electrochemical/wet chemical iodination of Cu foil and subsequent in situ electrochemical reduction reaction. In comparison to electropolished Cu (EP‐Cu), both E‐ID‐Cu and W‐ID‐Cu can produce multicarbon (C 2+ ) products with much‐improved selectivity, with Faradic efficiency (FE) reaching 64.39% for E‐ID‐Cu and 71.16% for W‐ID‐Cu at −1.1 V versus reversible hydrogen electrodes (RHE), which can be attributed to their localized geometry features with high defect density and high surface roughness. Given the well‐determined FEs towards C 2+ products, the partial current densities for C 2+ production can be estimated to be 251.8 mA cm −2 for E‐ID‐Cu and 290.0 mA cm −2 for W‐ID‐Cu at −1.2 V versus RHE in a flow cell. In situ characterizations and theoretical calculations reveal that the high‐density defects and high surface roughness can promote *CO adsorption by raising the d band center and then facilitate C–C coupling, contributing to the high selectivity of C 2+ products for ID‐Cu. Interestingly, the high surface roughness can increase the residence time of *C–H intermediates and decrease the formation energy of the *OCCO and*CH 3 CH 2 O intermediates, thus favoring C 2+ production, with a unique C 2 H 6 product observed over W‐ID‐Cu with FE of 10.14% at −0.7 V versus RHE.