Ketoenamine‐Linked Nitrogen‐Rich Covalent Organic Framework for Iodine Adsorption

ABSTRACT

As a relatively new class of materials, covalent organic frameworks (COFs) lack the structural diversity found in established porous materials. Therefore, developing novel covalent organic framework libraries is of substantial importance for broadening their application scope. In this study, using 2,4,6‐tris(formyl)phloroglucinol and carbohydrazide as monomers, nitrogen‐rich COFs was designed and synthesized through precise control of monomer stoichiometry and polycondensation conditions. The framework features a high density of nitrogen‐containing functional groups, resulting in a significant enhancement of chemical active site density. Comprehensive characterization including Powder x‐ray diffraction (PXRD), Brunauer–Emmett–Teller (BET) method, x‐ray photoelectron spectroscopy (XPS), and solid‐state nuclear magnetic resonance ( ¹³ C NMR) spectroscopy confirms that the synthesized material possesses a highly ordered crystalline structure, high specific surface area, and stable covalent linkage. Moreover, the framework exhibits exceptional thermal stability with decomposition onset above 450°C and maintains structural integrity under strongly acidic environments. The iodine ( ¹²⁷ I) adsorption performance of this nitrogen‐rich covalent organic framework was systematically evaluated, revealing a high adsorption capacity of 2.22 g g ⁻¹ . The high stability of this material under harsh conditions demonstrates promising application prospects in fields such as radioactive waste treatment and environmental remediation.