Design, transport efficiency and structure-activity relationship of sulfonated poly (aryl ether ketone) proton exchange membrane based on multi-functional MOFs

Abstract

In this paper, two kinds of metal-organic frameworks (MOFs) with proton conduction capability were successfully prepared and added into sulfonated poly (ether ketone sulfone) (C-SPAEKS) by organic-inorganic blending. Then two different series of proton exchange membranes (PEMs) were fabricated. The template used in MOFs was UiO-66-NH2 (UN), by introducing sulfonic acid groups and imidazole groups on the template, additional proton sources and proton transport sites were constructed. Such multifunctional MOFs contributed greatly to the proton transport efficiency and structure-activity relationship of C-SPAEKS. The sulfonic acid functionalized MOFs (USN), sulfonic-acid-imidazole bifunctional MOFs (IUSN) and composite PEMs were characterized by XRD, XPS, FT-IR, 1H NMR and SEM. The prepared PEMs all have excellent proton conductivity, in which the proton conductivity of C-SPAEKS/IUSN-3% could reach 0.234 S cm−1 (80 °C and 100% relative humidity). Nafion117 had a conductivity of 0.105 S cm−1 (80 °C and 100% relative humidity), so C-SPAEKS/IUSN-3% exhibited a great enhancement on proton conductivity. Moreover, the oxidation stability of C-SPAEKS/IUSN-3% membrane was 96.97%, which was 39.32% higher than that of C-SPAEKS. These results all indicated that the as-prepared MOFs have made great contribution to improving the comprehensive properties of the sulfonated poly (aryl ether ketone) proton exchange membrane.