Unprecedented Flux-Mediated Synthesis of Crystalline Polyimide Covalent Organic Frameworks Using the 4-Dimethylaminopyridine (DMAP)-Type Nucleophilic Catalyst for Use in Efficient Photosynthesis of H2O2

Photocatalytic H2O2 production from water and O2 represents a sustainable approach for clean chemical synthesis, but developing efficient and stable photocatalysts remains challenging. Herein, we report a novel 4-dimethylaminopyridine (DMAP)-type nucleophilic catalyst-mediated flux synthesis strategy to prepare crystalline polyimide covalent organic frameworks (PI-COFs) as efficient photocatalysts for H2O2 generation. Interestingly, by introducing molten DMAP as the reaction medium, we achieved three PI-COFs (DMAP-BNCOFs, DMAP-BBCOFs, and DMAP-NNCOFs) with significantly enhanced crystallinity and porosity compared to those obtained in conventional solvothermal synthesis. The optimized PI-COFs showed excellent photocatalytic activity, among which DMAP-BNCOFs could achieve a H2O2 production rate of 8051.4 μmol h-1 g-1 without the presence of any sacrificial agents under visible-light irradiation, representing the most efficient polymeric/framework photocatalysts ever reported. The photocatalyst demonstrated remarkable stability over 90 h of continuous operation with no activity loss. DMAP-BNCOFs exhibited a lower exciton binding energy and longer excited-state lifetime compared with those of DMAP-BBCOFs and DMAP-NNCOFs. Experimental and theoretical studies revealed that enhanced performance stems from the optimal electronic structure, efficient charge separation, and accelerated O2 activation. This work provides new insights into the flux synthesis approach and rational design of PI-COF photocatalysts and establishes an effective strategy for sustainable H2O2 production.