Adjust the arrangement of imidazole on the metal-organic framework to obtain hybrid proton exchange membrane with long-term stable high proton conductivity

Abstract

Metal-organic frameworks-based hybrid proton exchange membranes could combine the advantages of organic and inorganic materials with excellent chemical and physical stability and good proton conductivity. In this work, two kinds of functionalized MOFs were synthesized based on MOF-801. Imidazole@MOF-801 was prepared by the impregnation method, which mainly incorporated free imidazole molecules into the pores of the MOF-801. Imidazole-MOF-801 was obtained by in-situ method, which imidazole further acted as non-structural ligands to coordinate to the zirconium metal sites. Furthermore, the hybrid membranes were fabricated with synthesized MOFs as fillers and sulfonated poly (arylene ether ketone sulfone) containing carboxyl groups (C-SPAEKS) as organic matrix. The structures and morphologies of the prepared MOFs and hybrid membranes were characterized by 1H NMR, XRD, FT-IR and SEM. The PXRD results showed that Im@MOF-801 and Im-MOF-801 exhibited excellent stabilities in both water and acid. The proton conductivities of these hybrid membranes were much higher (0.023–0.066 S cm−1 at 30 °C, 0.050–0.128 S cm−1 at 90 °C) than that of pure C-SPAEKS (0.010S cm−1 at 30 °C, 0.024 S cm−1 at 90 °C). Moreover, C-SPAEKS/Im-MOF-801-4% could maintain a stable proton conductivity for more than 100 h. These results indicate that these hybrid membranes have potential as proton exchange membranes.