Cationic metal–organic framework porous membranes with high hydroxide conductivity and alkaline resistance for fuel cells

Abstract

Hydroxide conductivity and alkaline stability are challenging issues for anion exchange membrane fuel cells (AEMFCs). Here, a novel sandwiched anion exchange membrane (AEM) was prepared from porous bromomethylated poly(2,6-dimethyl-1,4-phenylene oxide) (BPPO) entrapped cationic metal–organic frameworks (MOFs) with a polyvinyl alcohol (PVA) coating on the two sides. The porous BPPO matrix prepared by a non-solvent induced phase separation (NIPS) method provides numerous interconnected nanopores and sponge-like walls and enhanced uptake of alkali. The entrapped cationic MOFs can work as OH⁻ conductive channels while the PVA coating can block the crossover of fuels such as methanol. The final membranes can reach an OH⁻ conductivity of 145 mS cm⁻¹ at 80 °C and a methanol permeability of 3.68 × 10⁻⁷ cm² s⁻¹, the performance of which is much higher than that in the existing literature.