Wang Qianxi, Lei Yuting, Cui Yunyi, Lin Jingruolan, Huang Wei, He Yi
National Collaborative Innovation Center for Nuclear Waste and Environmental Safety, School of National Defence Science & Technology, Southwest University of Science and Technology, Mianyang 621010, P. R. China.
ACS Appl Mater Interfaces. 2022 May 18;14(19):22643-22649. doi: 10.1021/acsami.2c04922. Epub 2022 May 5.
Thermogravimetric analysis (TGA) is a key material characterization method for studying the thermal stability and thermochemical process. However, the common TGA for bulk samples lacks sufficient spatial information, which blurs the intrinsic thermal decomposition characteristic and limits the understanding of the structure-performance relationship. Here, we report a dark-field microscope (DFM) method for studying thermal desorption process of I from I-loaded zeolitic imidazolate framework-8 (I@ZIF-8). Because of the high spatial resolution, DFM enables the imaging and tracking of the local mass loss of I in single I@ZIF-8 particles at different reaction temperatures. We obtain from the DFM images the single-particle thermogravimetric and differential thermogravimetric curves to evaluate the inherent thermal stability of single I@ZIF-8 particles. We also find the heterogeneous thermal decomposition property among different I@ZIF-8 particles. Furthermore, we demonstrate the capacity of DFM to quantitatively determine thermal kinetics parameters such as the diffusion coefficient and activation energy of I in individual and multiple ZIF-8 particles. These useful results are essential for developing high-efficient porous adsorbents for the capture of I.
热重分析（TGA）是研究材料热稳定性和热化学过程的关键表征方法。然而，用于块状样品的常规TGA缺乏足够的空间信息，这模糊了其固有的热分解特性，并限制了对结构-性能关系的理解。在此，我们报道了一种暗场显微镜（DFM）方法，用于研究负载碘的沸石咪唑酯骨架-8（I@ZIF-8）中碘的热脱附过程。由于具有高空间分辨率，DFM能够对不同反应温度下单颗I@ZIF-8颗粒中碘的局部质量损失进行成像和跟踪。我们从DFM图像中获得单颗粒热重曲线和微分热重曲线，以评估单颗I@ZIF-8颗粒的固有热稳定性。我们还发现了不同I@ZIF-8颗粒之间的非均相热分解特性。此外，我们证明了DFM能够定量测定热动力学参数，如碘在单个和多个ZIF-8颗粒中的扩散系数和活化能。这些有用的结果对于开发用于捕获碘的高效多孔吸附剂至关重要。
