Enhanced OH− conductivity and alkaline stability of AEM by pyrene stacking backbone for water electrolysis

Abstract

A burgeoning hydrogen technology utilizing anion exchange membranes (AEMs) has attracted increasing interest owing to its potential for cost-effective commercial values. Nonetheless, there are still challenges pertaining to conductivity and persistent stability. Herein, an innovative approach has been introduced to enhance the alkaline resistance and conductivity of AEMs via π-π interactions. The synergistic π-stacking networks in the polymer backbone induce long-range cation aggregation through directed self-assembly, generating ionic cluster microdomains. These nanoconfined environments elevate local hydroxide concentration, leading to the increased density of accessible ion hopping sites within the localized regions. Furthermore, the electron-donating effects of pyrene effectively reduce the electrostatic potential of the β-H adjacent to quaternary ammonium cations, thus increasing the energy barrier for OH⁻ nucleophilic attack. The obtained AEMs demonstrate exceptional performance, exhibiting both high conductivity (160 mS/cm) and excellent alkaline stability (merely 0.35% conductivity degradation after 1950 h in 2 M KOH at 80 °C). These good properties enable the membrane electrode assembly (MEA) to achieve the current density of 2.58 A/cm² at 1.8 V, while maintaining stable operation for over 700 h in durability testing.