Stable Dicationic Covalent Organic Frameworks Manifesting Notable Structure-Enhanced CO2 Capture and Conversion

Covalent organic frameworks (COFs) are a class of promising porous crystalline materials for both capturing and converting CO2 into high-value-added products. However, long synthesis time and the need for cocatalyst restrict its potential for CO2 conversion. Herein, bipyridine-based TAPT-BP-COF with high crystallinity as a skeleton is rapidly synthesized within only 1 h by the aid of supercritical CO2 (scCO2) activation. Then, the production of dicationic TAPT-BP2+-COF is accomplished by a quaternization reaction. The CO2 capture capacity of TAPT-BP2+-COF improved by 55.6% due to its CO2-philic groups (imine and triazine groups), polar groups (−OH), charged skeleton, and suitable pore size, thus ensuring sufficient CO2 around the catalytic active sites. Additionally, the outstanding structure-enhanced CO2 conversion performance is observed due to the presence of the synergistic effect between –OH and Br– in the TAPT-BP2+-COF skeleton. The rate-determining step of cycloaddition is significantly accelerated without any solvents and cocatalysts compared to individual TAPT-BP-COF and [OH-BP]2+[Br]2– (BP2+ moiety). Specifically, TAPT-BP2+-COF efficiently generates cyclic carbonate by heterogeneously catalyzing CO2-epoxide cycloaddition with the yield of 99.3% and has excellent stability that can be reused ten times without significant activity reduction. This work provides a novel perspective for the targeted design and rapid synthesis of charged dicationic COF-based catalysts for high efficiency and durability in CO2 capture and conversion.