Preparation of sp ² carbon-bonded π-conjugated COF aerogels by ultrasound-assisted mild solvothermal reaction for multi-functional applications

Molding COFs into aerogels from monomers can establish interpenetrating spatial network structures on the centimeter scale that increase the accessibility of dominant pore channels and the convenience of real application, which radically gets rid of the difficult reprocessing problems of insoluble and non-fusible powder COFs. However, the construction of bulk COF structures and achieving crystallinity are often incompatible, especially with sp² carbon-based COFs, whose powder synthesis has been quite demanding. Herein, for the first time, we report an efficient method to prepare sp² carbon-linked π-conjugated DFB-TMTA-COF (DT-COF) aerogels by an ultrasound-assisted mild solvothermal technique and freeze-drying. Particularly, unlike the typical synthesis methods of vacuum deoxygenation, high temperature and long reaction time, crystalline DT-COF aerogels can be obtained by reacting at 90 °C for 48 h without vacuum sealing. The fluffy, hierarchical porous flower-shaped microsphere clustering of DT-COF aerogels contributes to excellent mechanical properties and better host-guest interactions, which are favorable to utilize the benefits of the highly conjugated structure of channels. As a proof of concept, DT-COF aerogels have been used in absorption, batteries, and sensors, demonstrating enhanced functionality and effectiveness.