Unveiling Key Descriptors of Ionomer Materials for Enhanced Electrochemical CO 2 Reduction

Polymeric ionomers near the catalyst surface of CO 2 reduction reaction (CO 2 RR) electrodes affect their efficiency; however, their multifaceted properties complicate structure–activity relationship elucidation. Here, we synthesized polycarbazole-based anion-exchange (QPC) ionomers bearing varying functionalized side chains to explore this relationship. Comprehensive analysis in physicochemical properties, electrochemical activity, and operando ATR-SEIRAS revealed that functional group modification significantly influenced the intrinsic ionomer properties, thereby affecting the Ag catalyst properties, microenvironments of interfacial water structures, and reaction kinetics of the protonation step for CO 2 RR and the hydrogen evolution reaction (HER). Notably, the QPC-trimethyl phosphonium (TMP) ionomer induced favorable interfacial water structures, having a high proportion of strong H-…