title: Microfluidic approach toward continuous and ultrafast synthesis of metal-organic framework crystals and hetero structures in confined microdroplets.
abstract: Herein, we report a novel nanoliter droplet-based microfluidic strategy for continuous and ultrafast synthesis of metal-organic framework (MOF) crystals and MOF heterostructures. Representative MOF structures, such as HKUST-1, MOF-5, IRMOF-3, and UiO-66, were synthesized within a few minutes via solvothermal reactions with substantially faster kinetics in comparison to the conventional batch processes. The approach was successfully extended to the preparation of a demanding Ru3BTC2 structure that requires high-pressure hydrothermal synthesis conditions. Finally, three different types of core-shell MOF composites, i.e., Co3BTC2@Ni3BTC2, MOF-5@diCH3-MOF-5, and Fe3O4@ZIF-8, were synthesized by exploiting a unique two-step integrated microfluidic synthesis scheme in a continuous-flow mode. The synthesized MOF crystals were characterized by X-ray diffraction, scanning electron microscopy, and BET surface area measurements. In comparison with bare MOF-5, MOF-5@diCH3-MOF-5 showed enhanced structural stability in the presence of moisture, and the catalytic performance of Fe3O4@ZIF-8 was examined using Knoevenagel condensation as a probe reaction. The microfluidic strategy allowed continuous fabrication of high-quality MOF crystals and composites exhibiting distinct morphological characteristics in a time-efficient manner and represents a viable alternative to the time-consuming and multistep MOF synthesis processes.
authors.affiliation: Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH) , Pohang 790-784, Korea.
authors.forename: Marco
authors.initials: M
authors.lastname: Faustini
authors.forename: Jun
authors.initials: J
authors.lastname: Kim
authors.forename: Guan-Young
authors.initials: GY
authors.lastname: Jeong
authors.forename: Jin Yeong
authors.initials: JY
authors.lastname: Kim
authors.forename: Hoi Ri
authors.initials: HR
authors.lastname: Moon
authors.forename: Wha-Seung
authors.initials: WS
authors.lastname: Ahn
authors.forename: Dong-Pyo
authors.initials: DP
authors.lastname: Kim