As the high-power density and environmentally friendly energy resources, proton exchange membrane fuel cells (PEMFCs) have a promising future in portable power generation. Herein, the hybrid Nafion membranes of ionic hydrogen-bonded organic frameworks (iHOFs) for PEMFC applications are demonstrated. By adjusting the position of sulfonic groups on naphthalene disulfonic acid compounds, four iHOFs with different types of hydrogen bonds were synthesized successfully based on 1,1′-diamino-4,4′-bipyridylium and naphthalene disulfonic acid. The formation of hydrogen bond interactions between amino and sulfonate groups provides a rich hydrogen bond network, which makes such iHOFs have high conductivity, and the maximum value is 2.76 × 10–3 S·cm–1 at 100 °C and 98% RH. Besides, composite membrane materials were obtained by mixing Nafion and iHOFs, and the maximum proton conductivity values can achieve 1.13 × 10–2 S·cm–1 for 6%-iHOF-3/Nafion and 2.87 × 10–3 S·cm–1 for 6%-iHOF-4/Nafion membranes at 100 °C under 98% RH. Through the H2/O2 fuel cell performance test by using iHOF/Nafion as the solid electrolyte, the maximum power and current density values of hybrid membranes are 0.36 W·cm–2 and 1.10 A·cm–2 for 6%-iHOF-3/Nafion and 0.42 W·cm–2 and 1.20 A·cm–2 for 6%-iHOF-4/Nafion at 80 °C and 100% RH. This work provides a practicable approach for establishing high-performance proton exchange hybrid membranes by doping high proton-conducting iHOFs into the Nafion matrix.
The development of high-performance proton exchange membrane fuel cells (PEMFCs) is crucial yet challenging. Enrichment of proton transport pathways by doping ionic hydrogen-bonded organic frameworks (iHOFs) in Nafion matrix is important for further development of high-performance PEMFCs. In this work, an iHOF material (iHOF-9) based on arylphosphonate anions and guanidinium cations with the three-dimensional (3D) hydrogen-bonded network was synthesized, which exhibits an ultrahigh proton conductivity of 4.38 × 10–2 S·cm–1 at 90 °C and 98% RH. In addition, by mixing iHOF into Nafion matrix, we have fabricated the high-performance hybrid membranes, and the maximum proton conductivity value can achieve 6.61 × 10–2 S·cm–1 for 9%-iHOF-9/Nafion membrane at 90 °C and 98% RH. iHOF-9/Nafion membranes were used to fabricate the proton exchange membranes for application in H2/O2 fuel cells. The maximum power density of 9%-iHOF-9/Nafion reached 1092.07 mW·cm–2 after stabilization for 10 h at 80 °C and 100% RH, which is a 33.99% improvement compared to the recast Nafion membrane. This work doped ultrahigh conductivity iHOF into the Nafion matrix as an emerging proton exchange membrane material, injecting new possibilities for the development of new energy sources.
Over the past two decades, progress in chemistry has generated various types of porous materials for removing iodine (129 I or 131 I) that can be formed during nuclear energy generation or nuclear waste storage. However, most studies for iodine capture are based on the weak host-guest interactions of the porous materials. Here, we present two cationic nonporous macrocyclic organic compounds, namely, MOC-1 and MOC-2, in which 6Iand 8I À were as counter anions, for highly efficient iodine capture. MOC-1 and MOC-2 were formed by reacting 1,1'diamino-4,4'-bipyridylium di-iodide with 1,2-diformylbenzene or 1,3-diformylbenzene, respectively. The presence of a large number of I À anions results in high I 2 affinity with uptake capacities up to 2.15 g • g À 1 for MOC-1 and 2.25 g • g À 1 for MOC-2.
Herein, we prepared three ionic hydrogen-bonded organic frameworks (iHOFsby organic acid−base reactions (H 2 L a1 = 1,5-naphthalene disulfonic acid, NaHL a2 = monosodium 3-amino-2,7-naphthalenedisulfonate, L b1 = 3,3′diaminobenzidine, and L b2 = 4,4′-diaminodiphenylmethane). There were abundant weak hydrogen bonds and strong ionic bonding interactions between anions and cations in the three iHOF structures, which made them have good thermal stability and high conductivity. An alternating current impedance test showed that the proton conductivity of 1 could reach 1.16 × 10 −3 S•cm −1 at 100 °C and 98% relative humidity (RH), and the proton conductivity maximum of 2 and 3 was 1.63 × 10 −3 and 3.34 × 10 −4 S•cm −1 at 98% RH and 90 °C, respectively. iHOFs had been doped into the Nafion solution, and the hybrid membranes were triumphantly made. The proton conductivity of 6%-1/Nafion and 9%-2/Nafion was calculated to be 2.7 × 10 −3 (80 °C) and 1.0 × 10 −2 (100 °C) S•cm −1 at 98% RH, which were 2.3-and 6.2-fold higher than that of the original iHOFs, respectively.
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.
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