Electrocleavage Synthesis of Solution-Processed, Imine-Linked, and Crystalline Covalent Organic Framework Thin Films

Developing a general, facile, and direct strategy for synthesizing thin films of covalent organic frameworks (COFs) is amajor challenge in thisfield. Herein, we report an unprecedented electrocleavage synthesis strategy to produce imine-linked COFfilms directly on electrodes from electrolyte solutions at room temperature. This strategy enables the cathodic exfoliation of the COFpowders to nanosheets by electrochemical reduction and protonation, followed by nanosheets migrating to the anode andreproducing the COF structures by anodic oxidation. Our method is adaptable with most imine-linked COFs by virtue of the lowredox potential of the imine bonds, whereas the COFfilms possess high crystallinity and hierarchical porosity. We highlight theseCOFfilms as a superb platform for promoting mass transfer by demonstrating their extraordinarily rapid iodine adsorption with record-high rate constants.