Application of Ionic Hydrogen-Bonded Organic Framework Materials in Hybrid Proton Exchange Membranes

Abstract

Excellent and inexpensive materials with proton conductivity have far-reaching significance for the development of clean energy. In this paper, three ionic hydrogen-bonded organic frameworks (iHOFs) were synthesized using naphthalenedisulfonate derivatives with substituents at different positions and 1,1′-diamino-4,4′-bipyridylium. The hydrogen bond networks were formed by sulfonic acid groups and amino groups, while the addition of functional groups such as hydroxyl or amino groups can also enrich the hydrogen bonds, which also makes such iHOFs have high conductivity, in which iHOF-7 afforded the highest proton conductivity of 4.5 × 10–3 S·cm–1 at 100 °C, 85% relative humidity (RH). It is difficult for the crystalline materials to form a membrane, so we prepared the hybrid membranes of iHOF-7 using sulfonated poly (ether ether ketone) (SPEEK) or chitosan (CS) as the supporting polymeric matrix. At 85% RH and 100 °C, the highest proton conductivity of the 15%-iHOF-7/SPEEK composite membrane can reach 5.1 × 10–3 S·cm–1, and at 98% RH and 100 °C, the highest proton conductivity of 15%-iHOF-7/CS can reach to 5.7 × 10–3 S·cm–1.

Hydrogen-bonded organic frameworks for membrane separation

“…The improved full-cell performance in the 6%-iHOF-4/Nafion hybrid membrane could be attributed to the richer hydrogen bond network present in its structure compared to the 6%-iHOF-3/Nafion hybrid membrane. In another study, Cao et al 36 presented three iHOFs, namely iHOF-5, iHOF-6, and iHOF-7. These iHOFs were created by combining sulfonic acid and amino groups through hydrogen bond interaction.…”

Charge‐Assisted Ionic Hydrogen‐Bonded Organic Frameworks: Designable and Stabilized Multifunctional Materials

“…[132] Similarly, naphthalene disulfonate derivatives with different substituents and DBpy * 2I were self-assembled in the solvent by chargeassisted hydrogen-bonded to give iHOF-5-7, with the solvent molecules acting as the connecting points to link intermolecularly unbonded sulfonate and pyridinium amine groups in the crystalline structure. [152] Self-assembly using tetrakis(4sulfophenyl)ethylene and DBpy * 2I allowed both iHOF-10 and iHOF-11 to be synthesized using different solvents and iHOF-10 to be transformed into iHOF-11 after immersing it in water. [153] Water molecules enter into iHOF-10, replace the guest DMF molecules inside the crystal, and participate in the formation of the hydrogen-bonded structure of the crystal, which improves the stability of the structure and enhances the proton transport properties.…”

Latest progress in proton-conducting hydrogen-bonded organic frameworks

“…In 2023, L.-H. Cao and co-workers used 1,1′-diamino-4,4′-bipyridinediiodide (DBpy-2I) with disodium 3-hydroxy-2,7-naphthalenedisulfonate (Na 2 L 1 ), disodium 3,6-dihydroxy-2,7-naphthalene-disulfonate (Na 2 L 2 ), 7-Amino-1,3-naphthalenedisulfonic acid (H 2 L 3 ), forming iHOF-5 , iHOF-6 , iHOF-7 by creating H-bonds among the amino cation and the sulfonic acid anion. 128 For iHOF-5 , the asymmetric unit contains L 1 2− , a DBpy 2+ and three H 2 O molecules. The ligand molecules are attached to the H 2 O units by H-bonds, forming a one-dimensional H-bonding network.…”