A crystalline covalent organic framework embedded with a crystalline supramolecular organic framework for efficient iodine capture

Abstract

Supramolecular organic frameworks (SOFs) and covalent organic frameworks (COFs) have been the focus of researchers for a long time because of their regular periodic structure and good crystalline morphology. However, the relatively limited stability of SOFs and the slightly insufficient functionality of COFs have restricted the further applications of these materials to some extent. Herein, we report for the first time a COF & SOF bicrystalline composite based on a triazine COF and a bisbenzimidazole SOF, which combines the excellent stability and uniform pore support of COFs with the advantage of abundant and diverse active functional sites of SOFs. The as-produced composite has better stability, adsorption performance for gaseous iodine and recycling utilization rate than the single COF and SOF materials, with the highest adsorption capacity of up to 4.46 g g⁻¹, which benefits from the abundant active adsorption sites brought about by the SOF. The design and construction strategy of bicrystalline composites in this study can not only effectively solve the problem of poor stability of traditional SOFs which makes it difficult to meet the practical application requirements, but also greatly improve the variety and number of functional sites of COFs, which creates the conditions for the improvement and enhancement of the application properties of the materials and has great popularization and application value.