Study on preparation and performance of sulfonated polyaryl ether nitrile@Im-MOF-801 (SPEN@Im-MOF-801) composite proton exchange membrane

Sulfonated polyaryl ether nitrile (SPEN) is some of the most viable novel materials to replace the Nafion membrane. To resolve the issue of proton conductivity in fuel cells with poor sulfonation degree polyaryl ether nitrile cell membranes. A metal-organic structure (MOF-801) was added as a filler, and imidazole was loaded by the MOF-801 structural skeleton via a chemical ligand to improve the SPEN’s proton conductivity. The expected chemical structure of im-MOF-801 and SPEN@Im-MOF-801 was confirmed by using FTIR and ¹H NMR. Loading im-MOF-801 into SPEN resulted in SPEN@Im-MOF-801 composite proton exchange membranes. The impacts of the metal-organic framework on the performance of SPEN composite membranes were explored by assessing their mechanical characteristics, thermal stability, proton conductivity, and methanol permeability. The results show that the composite has outstanding thermal and mechanical stability. The tensile strength of membranes rose from 25.92 MPa to 39.34 MPa compared to the castings SPEN membrane, which was attributable to creating a hydrogen-bonding network between im-MOF-801 and SPEN, which boosted intermolecular forces. The carboxyl and hydroxyl groups in im-MOF-801 gave additional acceptors and donors that expanded the proton conductivity of SPEN, which was 16.19 ×10⁻² S·cm⁻¹ and expanded continuously, followed by a decrease with increasing temperature. Proton conductivity of SPEN@Im-MOF-801–3 and im-MOF-801–9 comes to 18.46 and 17.07 ×10⁻² S·cm⁻¹ at 80°C. Moreover, the methanol penetration of SPEN@Im-MOF-801 decreased reliably (from 5.32 to 1.02 ×10⁻⁷ S·cm⁻¹ which was much lower than that of the Nafion film 21.87 ×10⁻⁷ S·cm⁻¹). Subsequently, the most noteworthy selectivity of SPEN@Im-MOF-801–3 comes to 2.93×10⁵ S·cm⁻³·s⁻¹, which is approximately 8.9 times higher than that of Nafion (0.33×10⁵ S·cm⁻³·s⁻¹). The comes about demonstrates that these composites have potential applications in DMFCs.