Growth Process of Two-Dimensional Metal-Organic Framework Cu- BDC: A Particle Attachment Crystallization Mechanism Revealed by Microdroplet Flow Reaction

Two-dimensional (2D) metal-organic frameworks (MOFs) have attracted significant attention because of their exotic physicochemical properties. However, the whole picture of the reaction-crystallization process of 2D MOFs remains ambiguous. Unlike common batch-scale reactors, the microdroplet flow (MF) reaction allows for accurate controlling of reaction time, temperature, and reactant concentration, rendering it a technique that is especially well-suited for studying the crystallization processing of MOFs. Here, different statuses of Cu-BDC during the crystal growth process were successfully captured and the nonclassical crystallization mechanism of 2D MOFs was revealed through the MF reaction technique. Benefiting from more accessible exposed active site on the surface, the intermediate state product of Cu-BDC nanosheets exhibited better catalysis performance in the oxidative cyclization reaction. This mechanism of the 2D Cu-BDC growth process is promising for the rational design of various 2D MOFs with special structures.

Automated summary

Two-dimensional metal-organic frameworks have been widely studied due to their unique properties. However, the process of crystallization in these frameworks is not well understood. Using the microdroplet flow reaction technique, researchers were able to capture different states of Cu-BDC during crystal growth and uncover a nonclassical crystallization mechanism. The intermediate state product of Cu-BDC nanosheets showed enhanced catalytic performance due to its accessible active sites. This finding can guide the rational design of various 2D MOFs with special structures.