Regulating Interfacial Water Distribution and Ion Transport by Rigid-Flexible Dual-Piperidinium Ionomer toward Enhanced CO ₂ Electrolysis

The precise regulation of interfacial microenvironments by ionomers in membrane electrode assembly electrolyzers for CO 2 reduction plays a pivotal role in determining their overall catalytic performance. Conventional anion exchange ionomers possess rigid molecular backbones that limit their ability to dynamically respond to the interfacial electric field. Herein, we report that a rigid-flexible dual-piperidinium anion exchange ionomer (DQ 15 ) markedly enhances the CO 2 -to-CO conversion on silver nanoparticles at industrial-level current densities. Operando electrochemical impedance spectroscopy with distribution of relaxation times analysis, in conjunction with in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy, reveals that the DQ 15 ionomer boosts ion conductivity at the triple-phase boundary by providing additional ion exchange sites and enriches local CO 2 by disrupting the hydrogen-bond network of interfacial H 2 O, thus promoting the apparent CO 2 -to-CO electroreduction kinetics.