Controlling the surface oxidation state of halogenated Cu-based catalyst for electrochemical reduction of carbon dioxide to ethylene

Abstract

The electrochemical CO2 reduction reaction (CO2RR) has attracted significant attention as strategy for achieving carbon neutrality. Among the candidate materials for the CO2RR, Cu-based electrocatalysts can potentially produce various high-value carbon products. However, the diversity of their products obtained via CO2RR induces low selectivity and hinders the acquisition of a specific product with a high yield. Herein, we suggest the strategies for enhancing ethylene production via CO2RR by reconstructing the oxidation states of the Cu-based catalysts. The introduced chemical oxidation and following halogenation contributes to modulate the electron structures and oxidation states of the electrodeposited polygonal Cu catalyst surface. In particular, the chemical oxidation step induces the coexistence of Cu0 and Cu+ on the catalyst surface which stabilize the CO2 adsorption onto the catalyst surface, and the halogenation maintains the Cu0/Cu+ ratio of the catalyst surface during the CO2RR. As a result, controlling the oxidation states of Cu-based catalyst improves the ethylene production selectivity up to 47.0 % of Faradaic efficiency. Furthermore, we employ a membrane electrode assembly-based electrolyzer for CO2RR which is used for commercialization, and achieve high ethylene production with a partial current density of 124.7 mA cm–2.