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Abstract：
Metal-organic frameworks (MOFs) are a promising class of porous materials for the design of gas sensing arrays, which are often called electronic noses. Due to their chemical and structural tunability, MOFs are a highly diverse class of materials that align well with the similarly diverse class of volatile organic compounds (VOCs) of interest in many gas detection applications. In principle, by choosing the right combination of cross-sensitive MOFs, layered on appropriate signal transducers, one can design an array that yields detailed information about the composition of a complex gas mixture. However, despite the vast number of MOFs from which one can choose, gas sensing arrays that rely too heavily on distinct chemistries can be impractical from the cost and complexity perspective. On the other hand, it is difficult for small arrays to have the desired selectivity and sensitivity for challenging sensing applications, such as detecting weakly adsorbing gases with weak signals, or conversely, strongly adsorbing gases that readily saturate MOF pores. In this work, we employed gas adsorption simulations to explore the use of a variable pressure sensing array as a means of improving both sensitivity and selectivity as well as increasing the information content provided by each array. We studied nine different MOFs (HKUST-1, IRMOF-1, MgMOF-74, MOF-177, MOF-801, NU-100, NU-125, UiO-66, and ZIF-8) and four different gas mixtures, each containing nitrogen, oxygen, carbon dioxide, and exactly one of the hydrogen, methane, hydrogen sulfide, or benzene. We found that by lowering the pressure, we can limit the saturation of MOFs, and by raising the pressure, we can concentrate weakly adsorbing gases, in both cases, improving gas detection with the resulting arrays. In many cases, changing the system pressure yielded a better improvement in performance (as measured by the Kullback-Liebler divergence of gas composition probability distributions) than including additional MOFs. We thus demonstrated and quantified how sensing at multiple pressures can increase information content and cross-sensitivity in MOF-based arrays while limiting the number of unique materials needed in the device.
摘要：
金属有机框架（MOFs）是一类有前途的多孔材料，用于设计气敏阵列，通常被称为电子鼻。由于它们的化学和结构可调性，MOF是高度多样化的材料类别,其与在许多气体检测应用中感兴趣的类似多样化的挥发性有机化合物(VOC)类别很好地匹配。原则上,通过选择正确的交叉敏感MOFs组合，在适当的信号传感器上分层，人们可以设计一个阵列，产生有关复杂气体混合物组成的详细信息。然而,尽管可以选择大量的MOF，从成本和复杂性的角度来看，过于依赖不同化学物质的气体传感阵列可能是不切实际的。另一方面,对于具有挑战性的传感应用，小阵列很难具有所需的选择性和灵敏度，例如检测具有弱信号的弱吸附气体，或者相反，强烈吸附容易饱和MOF孔的气体。在这项工作中,我们使用气体吸附模拟来探索使用可变压力传感阵列作为提高灵敏度和选择性以及增加每个阵列提供的信息内容的手段。我们研究了九种不同的MOF（HKUST-1，IRMOF-1，MgMOF-74，MOF-177，MOF-801，NU-100，NU-125，UiO-66和ZIF-8）和四种不同的气体混合物，每个都含有氮，氧气,二氧化碳,其中一个氢，甲烷,硫化氢,或者苯.我们发现通过降低压力，我们可以限制MOFs的饱和度，通过增加压力，我们可以浓缩弱吸附气体，在这两种情况下，改善与所得阵列的气体检测。在许多情况下,与包括额外的MOF相比，改变系统压力可以更好地改善性能（通过气体成分概率分布的Kullback-Liebler发散来衡量）。因此，我们证明并量化了在多个压力下的感测如何增加基于MOF的阵列中的信息内容和交叉灵敏度，同时限制了设备中所需的独特材料的数量。
