Improved CO Selectivity via Anion Exchange Membrane Electrode Assembly-Type CO2 Electrolysis with an Ionomer-Coated Zn-Based Cathode

Abstract

Zn is a promising electrocatalyst candidate for CO production via CO2 electrolysis because of the moderate binding energy of * COOH intermediate. However, its thermodynamically unstable properties could cause performance degradation, particularly in conventional H-type electrolysis systems where the electrocatalyst is directly in contact with the electrolyte. Herein, we investigate the unstable characteristics of Zn-based cathode and suggest employing the anion exchange membrane electrode assembly- (AEMEA-) type CO2 electrolysis system to mitigate the electrolyte effects and enhance the catalytic performance. Unlike the conventional H-type electrolyzer, an AEMEA-type electrolyzer with a zero-gap configuration could mitigate the electrolyte effects on the cathode, thereby suppressing surface oxidation of the Zn-based cathode during the electrochemical reaction. Furthermore, the anion exchange ionomer layer on the cathode provides numerous ion pathways between catalyst and membrane interfaces and increases catalyst utilization that enhances the activity and selectivity for CO production via CO2 electrolysis. The above results suggest the breakthrough of using unstable materials as a catalyst for CO2 electrolysis and achieving reasonable performance.