A Computational Study of Isopropyl Alcohol Adsorption and Diffusion in UiO-66 Metal-Organic Framework: The Role of Missing Linker Defect.
A Computational Study of Isopropyl Alcohol Adsorption and Diffusion in UiO-66 Metal-Organic Framework: The Role of Missing Linker Defect.
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DOI：
10.1021/acs.jpcb.0c11252
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发表时间：
2021-04
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影响因子：
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通讯作者：
Shanshan Wang;Madeleine C. Oliver;Y. An;Enyi Chen;Zhibin Su;A. Kleinhammes;Yue Wu;Liangliang Huang
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作者：
Shanshan Wang;Madeleine C. Oliver;Y. An;Enyi Chen;Zhibin Su;A. Kleinhammes;Yue Wu;Liangliang Huang
缺陷工程导致金属有机框架（MOFs）的物理和化学性质的有效操纵。以常见的缺失接头缺陷为例，缺陷MOF通常具有较大的孔和较大的表面积/体积比，这两者都有利于增加吸附量。然而，当涉及到MOFs中吸附物的自扩散时，缺少的连接体是一把双刃剑：由于缺少连接体，不饱和金属位点可能与吸附物发生更强烈的相互作用，导致自扩散较慢。因此，它是至关重要的，以评估这两个竞争因素，并揭示哪一个是占主导地位的，一个更快的自扩散，由于较大的体积或较慢的自扩散，由于在不饱和网站的强相互作用。在这项工作中，通过Monte Carlo和分子动力学模拟，我们研究了异丙醇（IPA）在Zr基UiO-66 MOFs中的行为，特别关注缺失的连接子效应。结果表明，不饱和Zr位与IPA分子强烈结合，这反过来会显着降低IPA的自扩散系数。除此之外，对于相同水平的缺失接头，缺陷位点的位置也会产生差异。我们期望这样的理论研究将提供对约束下自扩散的深入理解，激发更好的缺陷工程策略，并促进基于MOF的材料走向具有挑战性的现实应用。
Defect engineering leads to an effective manipulation of the physical and chemical properties of metal-organic frameworks (MOFs). Taking the common missing linker defect as an example, the defective MOF generally possesses larger pores and a greater surface area/volume ratio, both of which favor an increased amount of adsorption. When it comes to the self-diffusion of adsorbates in MOFs, however, the missing linker is a double-edged sword: the unsaturated metal sites, due to missing linkers, could interact more strongly with adsorbates and result in a slower self-diffusion. Therefore, it is of fundamental importance to evaluate the two competing factors and reveal which one is dominating, a faster self-diffusion due to larger volume or a slower self-diffusion owing to strong interactions at unsaturated sites. In this work, via Monte Carlo and molecular dynamics simulations, we investigate the behavior of isopropyl alcohol (IPA) in the Zr-based UiO-66 MOFs, with a specific focus on the missing linker effects. The results reveal that unsaturated Zr sites bind strongly with IPA molecules, which in return would significantly reduce the self-diffusion coefficient of IPA. Besides this, for the same level of missing linkers, the location of defective sites also makes a difference. We expect such a theoretical study will provide an in-depth understanding of self-diffusion under confinement, inspire better defect engineering strategics, and promote MOF based materials toward challenging real-life applications.