近日，我校化学与化工学院曹丽慧教授团队围绕离子型氢键有机框架（iHOFs）材料的质子传导及燃料电池应用开展了一系列研究工作，在Advanced Functional Materials（IF = 18.5）、Chemical Engineering Journal（IF = 13.3）、ACS Materials Letters（IF = 9.6）期刊上发表了三篇研究论文，并受邀撰写电荷辅助iHOFs材料的设计合成及应用的相关综述（Chemistry-A European Journal, 2024, 30, e202303580）。
氢键有机框架（HOFs）是由有机分子单元通过非共价氢键相互作用构建而成的晶体，分子间作用力较弱，因此合成和设计具有超质子传导性和稳健性的氢键有机框架相对困难。通过酸碱配对策略自组装的离子氢键有机框架（iHOFs），由于具有丰富的氢键、强离子键以及π-π堆积等相互作用使之成为可能，结构中丰富的氢键为质子提供了独特的输运路径。同时，iHOFs中的酸碱有机分子可作为质子载体或质子源，有效地传输质子，可获得具有超质子导电性的材料。
本文利用联苯二磷酸和1,1’-二氨基-4,4’-二联吡啶为原料制备了一例大尺寸的三维（3D）氢键网络结构iHOF-16，该材料具有优异的热稳定性和化学稳定性，在强酸碱条件下也能保持高结晶度和坚固的结构。iHOF-16沿a轴、b轴和c轴方向分别具有0.388、5.56×10-3和3.25×10-4 S cm-1的高各向异性质子传导率。利用密度泛函理论（DFT）计算结果表明质子最容易在a轴方向传输，从而产生超质子传导率。通过电荷辅助合成策略，为设计稳定的超质子导电材料提供了一种可行的方法。
相关成果以“An Ultra-Robust and 3D Proton Transport Pathways iHOF with Single-Crystal Superprotonic Conductivity Around 0.4 S·cm−1”为题，发表在Advanced Functional Materials（IF = 18.5）上。陕西科技大学为论文第一通讯单位，化学与化工学院2023级博士研究生曹萧杰为该论文的第一作者，曹丽慧教授为第二作者和论文唯一通讯作者。
本工作以1,3,5-三（4-膦酸基苯基）苯与盐酸胍为原料，在二甲胺调节的作用下，成功制备了两种iHOFs（即iHOF-14、iHOF-15）。其中，胍阳离子和芳基膦酸阴离子通过电荷辅助氢键增强了框架的稳定性。由于丰富的氢键网络，iHOF-14和iHOF-15表现出超过10-2 S·cm-1的质子导电性。此外，我们将iHOFs掺杂到Nafion基质中，得到了具有更丰富的质子传输路径和良好的甲醇阻隔性能的PEM。在100 °C和98% RH下，9%-iHOF-14/Nafion和9%-iHOF-15/Nafion电导率分别达到1.53 × 10-1和1.78 × 10-1 S·cm-1。72 h的甲醇渗透实验结果表明，复合膜的甲醇渗透率比重铸后的Nafion低73.7%。用于DMFCs的混合膜的最大功率密度约为80 mW·cm-2，是重铸Nafion的1.5倍。这一工作不仅丰富了芳基膦酸盐iHOFs，而且拓展了用于DMFC的iHOFs/Nafion PEM材料。
相关成果以“Dimethylamine-tuned guanidinium arylphosphonate iHOFs and superprotonic conduction Nafion hybrid membranes for DMFCs”为题，发表在Chemical Engineering Journal（IF = 13.3）上。陕西科技大学为论文唯一通讯单位，化学与化工学院2022级博士研究生白向田为该论文的第一作者，曹丽慧教授为论文唯一通讯作者。
本文以六(4-磺酸基苯基)苯和1,1’-二氨基-4,4’-二联吡啶为原料合成了具有三维氢键网络的iHOF-13。稳定的iHOF是通过电荷辅助氢键相互作用连接，并通过静电吸引进一步加强。同时，结晶水分子的存在促进了更广泛的氢键网络形成，从而使iHOFs具有超质子导电性。具体来说，iHOF-13在98% RH和100 °C下的质子电导率为1.3 × 10-1 S·cm-1。iHOF富含质子输运位点，其掺杂到Nafion基体中表现出极高的质子电导率（10-1 S·cm-1）和低的甲醇渗透率。在直接甲醇燃料电池中，7.5%-iHOF-13/Nafion复合膜的最大功率密度可达104.7 mW·cm-2，是重铸Nafion的2.1倍。高性能iHOF的加入有助于增强质子传输途径，同时有效抑制甲醇交叉，从而扩大其在燃料电池中的潜在应用。
相关成果以“Arylsulfonate Ionic Hydrogen-Bonded Organic Frameworks Enable Highly Stable and Superprotonic Conductivity for Enhancing Direct Methanol Fuel Cells” 为题，发表在ACS Materials Letters上（IF = 9.6）上。陕西科技大学为论文唯一通讯单位，化学与化工学院2022级博士研究生白向田为该论文的第一作者，曹丽慧教授为论文唯一通讯作者。
以上研究成果得到国家自然科学基金（22075169）和陕西基础科学（化学、生物学）研究院科学研究计划项目（22JHQ026）的支持。
原文链接：https://doi.org/10.1002/adfm.202409359
https://doi.org/10.1016/j.cej.2024.150747
https://doi.org/10.1021/acsmaterialslett.4c00953
https://doi.org/10.1002/chem.202303580
附：曹丽慧教授团队近三年代表性论文：
1. X.-J. Cao, L.-H. Cao*, X.-T. Bai, X.-Y. Hou, H.-Y. Li, An Ultra-Robust and 3D Proton Transport Pathways iHOF with Single Crystal Superprotonic Conductivity Around 0.4 S·cm−1, Adv. Funct. Mater., 2024, 2409359. (IF2023=18.5)https://doi.org/10.1002/adfm.202409359
2. X.-T. Bai, L.-H. Cao*, X.-Y. Chen, S.-H. Li, J.-H. Zhang, Dimethylamine-tuned guanidinium arylphosphonate iHOFs and superprotonic conduction Nafion hybrid membranes for DMFCs, Chem. Eng. J., 2024, 487, 150747. (IF2023=13.3)https://doi.org/10.1016/j.cej.2024.150747
3. X.-T. Bai, L.-H. Cao*, F. Zhao, and S.-H. Li, Arylsulfonate Ionic Hydrogen-Bonded Organic Frameworks Enable Highly Stable and Superprotonic Conductivity for Enhancing Direct Methanol Fuel Cells, ACS Materials Lett., 2024, 6, 3351−3357. (IF2023=9.6)https://doi.org/10.1021/acsmaterialslett.4c00953
4. M.-F. Huang, L.-H. Cao*, and B. Zhou, A solvent-controlled photoresponsive ionic hydrogen-bonded organic framework for encryption applications, Chem. Commun., 2024, 60, 3437–3440. (IF2023=4.3)https://doi.org/10.1039/D4CC00701H
5. X.-Y. Chen, L.-H.Cao*, X.-T. Bai, and X.-J. Cao, Charge-Assisted Ionic Hydrogen-Bonded Organic Frameworks: Designable and Stabilized Multifunctional Materials, Chem. Eur. J., 2024, 30, e202303580. (Invited Review, IF2023=3.9)https://doi.org/10.1002/chem.202303580
6. X.-T. Bai, L.-H. Cao*, C. Ji, F. Zhao, X.-Y. Chen, X.-J. Cao, and M.-F. Huang, Ultra-High Proton Conductivity iHOF Based on Guanidinium Arylphosphonate for Proton Exchange Membrane Fuel Cells, Chem. Mater., 2023, 35, 3172−3180. (IF2023=7.2)https://doi.org/10.1021/acs.chemmater.2c03817
7. X.-Y. Chen, L.-H. Cao*, X.-T. Bai, X.-J. Cao, D. Yang, and Y.-D. Gao, Superprotonic Conductivity of Guanidinium Organosulfonate Hydrogen-Bonded Organic Frameworks with Nanotube-Shaped Proton Transport Channels, Precis. Chem., 2023, 1, 608−615. (新刊无影响因子)https://doi.org/10.1021/prechem.3c00094
8. F. Zhao, L.-H. Cao*, and C. Ji, Proton conduction of an ionic HOF with multiple water molecules and application as a membrane filler in direct methanol fuel cells, J. Mater. Chem. C, 2023, 11, 15288-15293. (IF2023=5.7)https://doi.org/10.1039/D3TC03123C
9. X.-Y. Chen, L.-H. Cao*, M.-F. Huang, Y. Yang, Y.-D. Gao, X.-T. Bai, and D. Yang, Water-Induced Single-Crystal to Single-Crystal Transformation of Ionic Hydrogen-Bonded Organic Frameworks with Enhanced Proton Conductivity, Chem. Eur. J., 2023, 29, e202300028. (IF2023=3.9)https://doi.org/10.1002/chem.202300028
10. X.-T. Bai, L.-H. Cao*, X.-Y. Chen, X.-J. Cao, W.-C. Meng, and K.-Y. Yan, A Sodium-Based Phosphonates Metal−Organic Framework with Superprotonic Conductivity, Cryst. Growth Des., 2023, 23, 8488−8493. (IF2023=3.2)https://doi.org/10.1021/acs.cgd.3c01102
11. F. Zhao, L.-H. Cao*, X.-T. Bai, X.-Y. Chen, and Z. Yin, Application of Ionic Hydrogen-Bonded Organic Framework Materials in Hybrid Proton Exchange Membranes, Cryst. Growth Des., 2023, 23, 1798−1804. (IF2023=3.2)https://doi.org/10.1021/acs.cgd.2c01306
12. Y. Yang, X.-Y. Chen, X.-M. Li, F. Zhao, X.-T. Bai and L.-H. Cao*, Enhanced proton conduction of crystalline organic salt hybrid membranes and the performance of fuel cells, Mater. Chem. Front., 2022, 6, 3402–3408. (IF2022=7.0)https://doi.org/10.1039/D2QM00656A
13. Y.-W. Tang, X.-Y. Chen, F. Zhao, X.-T. Bai, Z. Yin, and L.-H. Cao*, Enhanced Proton Conductivity of an Ionic Hydrogen-Bonded Organic Framework-Embedded Nafion Matrix, Energy Fuels, 2022, 36, 12772−12779. (IF2022=5.3)https://doi.org/10.1021/acs.energyfuels.2c02520
14. L.-H. Cao*, Y. Yang, X.-H. Tang, X. Wang, and Z. Yin, Substituent Controlled Framework Transformation Based on Solvent-Assisted Linker Exchange, Cryst. Growth Des. 2022, 22, 37-42. (IF2022=3.8) https://doi.org/10.1021/acs.cgd.1c00949
15. X.-Q. Xu, L.-H. Cao*, Y. Yang, F. Zhao, X.-T. Bai, and S.-Q. Zang, Hybrid Nafion Membranes of Ionic Hydrogen-Bonded Organic Framework Materials for Proton Conduction and PEMFC Applications, ACS Appl. Mater. Interfaces 2021, 13, 56566−56574. (IF2021=10.383) https://doi.org/10.1021/acsami.1c15748
16. L.-H. Cao*, X.-Q. Xu, X.-H. Tang, Y. Yang, J. Liu, Z. Yin, S.-Q. Zang, and Y.-M. Ma, Controllable Strategy for Metal−Organic Framework Light-Driven [2 + 2] Cycloaddition Reactions via Solvent-Assisted Linker Exchange, Inorg. Chem. 2021, 60, 2117−2121. (Supplementary Cover, IF2021=5.436)https://dx.doi.org/10.1021/acs.inorgchem.0c02999
17. X.-Q. Xu, L.-H. Cao*, Y. Yang, X.-T. Bai, F. Zhao, Z.-H. He, Z. Yin, and Y.-M. Ma, Cationic Nonporous Macrocyclic Organic Compounds for Multimedia Iodine Capture, Chem Asian J. 2021, 16, 142−146. (IF2021=4.839)https://doi.org/10.1002/asia.202001298
