Modulator-Assisted Photosynthesis: Green and Powerful Approach towards Superstructured π−Conjugated Covalent Organic Frameworks with Enhanced Electrochemical Performances

Graphical Modulator-assisted photosynthesis : The improvement of crystallinity and stability of covalent organic frameworks (COFs) is a great challenge. Here, the introduction of aromatic ortho-diamine as a dynamic modulator provide a powerful strategy to enhance the nucleation and crystal-growth process in photosynthesis, and result in π-conjugated COFs with high crystallinity, high stability, well-defined superstructures and excellent supercapacitance performances and metal-free 2e oxygen reduction reaction electrocatalytic activities. Fully aromatic π-conjugated covalent organic frameworks (COFs) have garnered great attention because of their potential applications in optoelectronics and energy storage; however, achieving crystallinity is far from trivial mainly because most covalent bond connection in these π-conjugated COFs have been deemed as an irreversible synthetic dead end because of aromatic stabilization. Here we report a green photosynthesis approach towards crystalline superstructured π-conjugated COFs, the introduction of aromatic-ortho-diamine (o-diamine) as dynamic modulator provide a powerful strategy to enhance the multi-scale structure control and resulted in π-conjugated COF with high crystallinity, rarely observed staggered AB stacking and uniform superstructured crystals of hundreds of micrometers. The mechanism behind this modulator-assisted photosynthesis approach is a polymerization-induced-crystallization process. The prepared π-conjugated crystalline framework displays superior electrochemical performance with a specific capacitance of more than 600 F g −1 at a scan rate of 10 mV s −1 , and excellent metal-free 2e oxygen reduction reaction (ORR) electrocatalytic activity with peak potentials of 0.764 V with excellent cycling stability, these values are among the highest electrochemical performance reported for COF materials.