Chemically stable porous crystalline macromolecule hydrazone-linked covalent organic framework for CO2 capture

Abstract

Existing Covalent Organic Frameworks (COFs) have shown conflicting and unstable properties and thus unreliable functions. Here, apart from the common low-pore size COFs, we offer a stable two-dimensional (2D) macromolecule hydrazone-linked COF with high average pore size to effectively capture CO2 due to its high surface area and N-rich porous structure. The highly crystalline COF macromolecule is synthesized under solvothermal conditions through the condensation of 2,4,6-tris(p-formylphenoxy)-1,3,5-triazine and oxalyl dihydrazide. The structure is characterized through Fourier transform infrared (FT-IR), Powder X-ray diffraction (PXRD), gas adsorption, Field emission scanning electron microscopy (FE-SEM), High resolution transmission electron microscopy (HR-TEM), Thermogravimetric analysis (TGA), and Atomic force microscopy (AFM) methods as well as computational simulations. The present 2D COF demonstrates excellent chemical stability in boiling water and strong acidic media. The exfoliation of COF in several solvents leads to thin COF nanosheets with maintained crystallinity and a periodic hexagonal order. The synthesized COF presents the CO2 capture of 0.9 mmol g−1 under 1 bar pressure at temperature 298 K. This work proposes a new procedure for the synthesis of macromolecule hydrazone-linked COF with relatively large pore size to adsorb CO2 with a reliable function.