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Kinetics and Mechanisms of ZnO to ZIF‐8 Transformations in Supercritical CO 2 Revealed by In Situ X‐ray Diffraction
Author(s) -
Sinnwell Michael A.,
Miller Quin R. S.,
Liu Lili,
Tao Jinhui,
Bowden Mark E.,
Kovarik Libor,
Barpaga Dushyant,
Han Yi,
Kishan Motkuri Radha,
Sushko Maria L.,
Schaef Herbert T.,
Thallapally Praveen K.
Publication year - 2020
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.202000434
Subject(s) - nucleation , supercritical fluid , kinetics , materials science , chemical engineering , crystallization , supercritical carbon dioxide , in situ , porosity , solvent , x ray crystallography , diffraction , chemical physics , chemistry , crystallography , organic chemistry , composite material , physics , optics , quantum mechanics , engineering
ZIF‐8 was synthesized in supercritical carbon dioxide (scCO 2 ). 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 scCO 2 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.