Observation of reduced thermal conductivity in a metal-organic framework due to the presence of adsorbates
Observation of reduced thermal conductivity in a metal-organic framework due to the presence of adsorbates
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DOI：
10.1038/s41467-020-17822-0
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发表时间：
2020-08-11
影响因子：
16.6
通讯作者：
Wilmer, Christopher E.
中科院分区：
文献类型：
--
作者：
Babaei, Hasan;DeCoster, Mallory E.;Wilmer, Christopher E.
吸附物的存在是否会增加或降低金属有机框架（MOFs）的热导率一直是一个悬而未决的问题。在这里，我们报告的观察在金属有机框架HKUST-1中的各种液体吸附物：水，甲醇和乙醇的存在下的热传输。对单晶和薄膜进行了实验热反射测量，并利用分子动力学模拟进行了理论预测。我们发现，HKUST-1的热导率下降了40 - 80%，这取决于吸附质，不能用有效介质近似解释的结果。我们的研究结果表明，吸附引入额外的声子散射HKUST-1，这特别缩短了低频声子模式的寿命。结果，系统导热率降低的程度大于通过产生附加传热通道所预期的增加。最后，我们表明，热扩散率甚至更大大降低比吸附的热导率。金属-有机骨架是用于气体储存和分离的有吸引力的吸附剂，但适当的散热对于实际应用是重要的。在这里，作者使用实验和理论来显示液体吸附物对金属有机框架中的热传输的影响。
Whether the presence of adsorbates increases or decreases thermal conductivity in metal-organic frameworks (MOFs) has been an open question. Here we report observations of thermal transport in the metal-organic framework HKUST-1 in the presence of various liquid adsorbates: water, methanol, and ethanol. Experimental thermoreflectance measurements were performed on single crystals and thin films, and theoretical predictions were made using molecular dynamics simulations. We find that the thermal conductivity of HKUST-1 decreases by 40 - 80% depending on the adsorbate, a result that cannot be explained by effective medium approximations. Our findings demonstrate that adsorbates introduce additional phonon scattering in HKUST-1, which particularly shortens the lifetimes of low-frequency phonon modes. As a result, the system thermal conductivity is lowered to a greater extent than the increase expected by the creation of additional heat transfer channels. Finally, we show that thermal diffusivity is even more greatly reduced than thermal conductivity by adsorption. Metal-organic frameworks are attractive adsorbents for gas storage and separations, but appropriate heat dissipation is important for practical application. Here the authors use experiment and theory to show the impact of liquid adsorbates on thermal transport in metal-organic frameworks.