Dong Xi-Yan, Wang Jun-Hao, Liu Shan-Shan, Han Zhen, Tang Qing-Jie, Li Fei-Fei, Zang Shuang-Quan
College of Chemistry and Chemical Engineering, Henan Key Laboratory of Coal Green Conversion , Henan Polytechnic University , Jiaozuo 454000 , China.
College of Chemistry and Molecular Engineering , Zhengzhou University , Zhengzhou 450001 , China.
ACS Appl Mater Interfaces. 2018 Nov 7;10(44):38209-38216. doi: 10.1021/acsami.8b12846. Epub 2018 Oct 23.
Metal-organic frameworks (MOFs) embedded in polymer have showed efficiency in improving proton conduction of hybrid membranes under hydrated conditions. However, anhydrous proton conduction of such hybrid membranes over 100 °C remains great challenge. Here, proton conductive hybrid membranes combined acid group (-SOH)- and basic group (-NH)-modified isomorphous MOFs, namely UiO-66(SOH) (abbreviated as A, the initial of acid) and UiO-66(NH) (abbreviated as B, the initial of basic) and a low-cost polymer (chitosan, CS) were prepared. The proton conductivity of the optimum dual MOF-cofilled hybrid membranes (CS/A + B) reached 3.78 × 10 S/cm at 120 °C and under anhydrous conditions, under which each component, that is MOF A, MOF B and CS, and single MOF-filled hybrid membranes (CS/A and CS/B) nearly lost proton conduction without exception, producing unprecedented results of one plus one more greater than two. The synergistic effects among UiO-66(SOH), UiO-66(NH), and CS on improving conductivity are also observed under hydrated conditions, the highest proton conductivity of CS/A + B reached 5.2 × 10 S/cm, which is 1.86, compared to that of the pure CS membrane at 100 °C and 98% relative humidity. The anhydrous proton conductivity of CS/A + B over 100 °C is one of the highest for MOF-based hybrid membranes. MOFs and hybrid membranes were extensively characterized and the proton conductive mechanism was revealed. The achievements open a new avenue for MOF-based anhydrous proton-conducting membranes and would advance the exploration of future application of these MOFs in fuel cells.
嵌入聚合物中的金属有机框架（MOF）已显示出在水合条件下提高混合膜质子传导效率的作用。然而，此类混合膜在100℃以上的无水质子传导仍然是巨大挑战。在此，制备了结合了酸基团（-SOH）和碱基团（-NH）修饰的同构MOF的质子传导混合膜，即UiO-66（SOH）（简称为A，酸的首字母）和UiO-66（NH）（简称为B，碱的首字母）以及一种低成本聚合物（壳聚糖，CS）。最佳的双MOF共填充混合膜（CS/A + B）在120℃和无水条件下的质子传导率达到3.78×10 S/cm，在此条件下，每个组分，即MOF A、MOF B和CS，以及单MOF填充的混合膜（CS/A和CS/B）无一例外几乎失去了质子传导，产生了一加一大于二的前所未有的结果。在水合条件下也观察到了UiO-66（SOH）、UiO-66（NH）和CS之间在提高传导率方面的协同效应，CS/A + B的最高质子传导率达到5.2×10 S/cm，与100℃和98%相对湿度下的纯CS膜相比为1.86。CS/A + B在100℃以上的无水质子传导率是基于MOF的混合膜中最高的之一。对MOF和混合膜进行了广泛表征并揭示了质子传导机制。这些成果为基于MOF的无水质子传导膜开辟了一条新途径，并将推动这些MOF在燃料电池未来应用方面的探索。
