Metal–organic frameworks with a large breathing effect to host hydroxyl compounds for high anhydrous proton conductivity over a wide temperature range from subzero to 125 °C
Metal–organic frameworks with a large breathing effect to host hydroxyl compounds for high anhydrous proton conductivity over a wide temperature range from subzero to 125 °C
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DOI：
10.1039/c5ta10765b
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发表时间：
2016-03
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通讯作者：
Yingxiang Ye;Xiuzhen Wu;Zizhu Yao;L. Wu;Zetao Cai;Lihua Wang;Xiuling Ma;Qianhuo Chen;Zhangjing Zha
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文献类型：
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作者：
Yingxiang Ye;Xiuzhen Wu;Zizhu Yao;L. Wu;Zetao Cai;Lihua Wang;Xiuling Ma;Qianhuo Chen;Zhangjing Zha
质子交换膜燃料电池(PEMFCs)用高性能质子导电材料的研制具有重要意义但仍具有挑战性，因为此类材料应满足以下要求：在较宽的温度范围内具有稳定的质子传输路径，在工作温度下具有较高的电导率，以及在起始温度下保持较高的电导率所需的小活化能Ea。在这里，我们首先证明了柔性金属有机骨架(FMOF)是为此类高性能质子导电材料寻找更好的质子载体的良好宿主。一种热稳定性高达400℃的FMOF[Zn3(Tz)2(Bdc)2]n(FJU-31，HTZ=1H-1，2，3-三氮唑，H2bdc=对苯二甲酸)被用来承载各种有机羟基作为新的质子载体。得到的三种FMOF(FJU-31@G，G=对苯二酚(HQ)、环己醇(CH)或丁醇(Bu))显示出高达65%的呼吸效应幅度和客体相关的单晶到单晶结构的转变。最重要的是，熔点高、pKa小的FJU-31@HQ对苯二酚表现出高的无水质子电导率2.65×10−4 S cm−1，低的活化能Ea为0.18 eV，以及在−40~125°C的最宽温度范围内稳定的质子在结晶多孔材料中的传导。
It is important but still challenging to develop high-performance proton conducting materials for proton exchange membrane fuel cells (PEMFCs), as such materials should meet the following requirements: stable proton-transport pathway over a wide temperature range, high conductivity at work temperature, and small activation energy Ea to maintain high conductivity at start temperature. Here, we firstly demonstrated that flexible metal–organic frameworks (FMOFs) are good hosts to seek out better proton carriers for such high-performance proton conducting materials. A FMOF [Zn3(tz)2(bdc)2]n (FJU-31, Htz = 1H-1,2,3-triazole, H2bdc = terephthalic acid) with high thermal stability up to 400 °C, which can be readily synthesized from the Zn5(tz)6(NO3)4 precursor and H2bdc, has been employed to host various organic hydroxyls as new proton carriers. Three resulting FMOFs Zn3(tz)2(bdc)2@G (FJU-31@G, G = hydroquinone (Hq), cyclohexanol (Ch) or butanol (Bu)) show large breathing effect amplitudes up to 65% and guest-related single-crystal to single-crystal structural transformations by temperature stimulus. Most importantly, FJU-31@Hq hosting hydroquinone with a high melting point and small pKa exhibits a high anhydrous proton conductivity of 2.65 × 10−4 S cm−1, low activation energy Ea of 0.18 eV, and the widest temperature range from −40 to 125 °C for stable proton conduction among the crystalline porous materials.