Membrane Engineering Reveals Descriptors of CO₂ Electroreduction in an Electrolyzer

Anion exchange membranes (AEMs) and ionomers are keys for electrochemical CO 2 reduction (eCO 2 R), but their development and multiple roles have not been intensively investigated. This study demonstrates HQPC-tmIM, a polycarbazole-based anion-conducting material, as a commercially viable AEM and reveals through multiphysics model simulation key descriptors governing eCO 2 R by exploiting the extraordinary membrane properties of HQPC-tmIM. The mechanical/chemical stability of HQPC-tmIM showed superior eCO 2 R performance in a membrane electrode assembly electrolyzer (MEA) in comparison to a commercial AEM (Sustainion). The CO partial current density ( j CO ) of −603 mA cm –2 on HQPC-tmIM MEA is more than twice that of Sustainion MEA and is achieved by only introducing HQPC-tmIM AEM and binder. The mutiphysics model revealed that the well-constructed membrane morphology of HQPC-tmIM leads to the outstanding membrane conductivity, and it enables high j CO through the facilitated charge transfer in overall reactions. This research suggests guidelines for developing a commercially viable AEM and ionomer for eCO 2 R.