ZIF-8 was synthesized in supercritical carbon dioxide (scCO2 ). In situ powder X-ray diffraction, ex situ microscopy, and simulations provide an encompassing view of the formation of ZIF-8 and intermediary ZnO@ZIF-8 composites in this nontraditional solvent. Time-resolved imaging exposed divergent physicochemical reaction pathways from previous studies of the growth of anisotropic ZIF-8 core@shell structures in traditional solvents. Synthetically relevant physiochemical properties of scCO2 were integrated into classical nucleation theory, relating interfacial forces, calculated through DFTB+ based molecular dynamics (MD), with 3D nucleation outcomes. The kinetics of crystallization were examined and displayed a characteristic signature of time- and temperature-dependent mechanisms over the extent of the reaction. Lastly, it is shown that subtle factors, such as the extent of reaction and the size/shape of sacrificial templates can tailor ZIF-8 composition and size, eliciting control over hierarchical porosity in a nonconventional green solvent.

中文翻译：

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原位X射线衍射揭示了超临界CO2中ZnO转变为ZIF-8的动力学和机理。

ZIF-8是在超临界二氧化碳（scCO2）中合成的。原位粉末X射线衍射，异位显微镜和模拟提供了在这种非传统溶剂中形成ZIF-8和中间ZnO @ ZIF-8复合材料的全面视图。时间分辨成像暴露了以前在传统溶剂中各向异性ZIF-8核壳结构生长研究的不同理化反应途径。scCO2的合成相关的理化性质被整合到经典的成核理论中，通过基于DFTB +的分子动力学（MD）计算的界面力与3D成核结果相关。检查了结晶的动力学，并在反应范围内显示了时间和温度依赖性机理的特征。最后，