Self-Assembly of Porphyrin to Realize the High Ionic Conductivity of Anion-Exchange Membranes
Li Sun, Yvonne Shuen Lann Choo, Wei Gao, Xue Lang Gao, Jia Hui Chen, Zhi Hong Cai, Jia Jun Wang, Qiu Gen Zhang, Ai Mei Zhu, Qinglin Liu
Abstract
In recent years, the microphase separation structure of ion-exchange membranes constructed by intermolecular interaction forces, such as hydrogen bond, cation–dipole interaction, and π–π interaction, has received extensive attention. Porphyrins can provide an active self-aggregation driving force through π–π interaction. Herein, a series of TMAP-Zn-PMHQ-X anion-exchange membranes (AEMs) were rationally designed in which the porphyrin was introduced to construct highly efficient ion channels. The as-prepared membranes are composed of functionalized fluorophobic polymers as the main chain and quaternized zinc porphyrin as the hydrophilic side chain. TMAP-Zn-PMHQ-13.5% with an ion-exchange capacity (IEC) of 0.35 meq·g–1 has an OH– conductivity of 152.5 mS·cm–1 and a swelling ratio of 53.3% at 80 °C. Meanwhile, the OH– conductivity of the membrane remains 95.76% after being tested in a 2 M NaOH solution at 80 °C for 500 h. A single cell based on the TMAP-Zn-PMHQ-13.5% AEM can achieve a power density of 631.6 mW·cm–2 at a current density of 998.9 mA·cm–2 at 80 °C. This kind of porphyrin self-assembled strategy provides an effective way to fabricate AEMs with good OH– conductivity and a relatively low IEC.