Abstract: The efficient capture and fixation of radioactive iodine in the air plays a critical role in nuclear environmental remediation and safety. Covalent organic frameworks (COFs), as a new class of porous materials, have demonstrated considerable potential for capturing gaseous iodine (I₂). To enhance the efficiency of radioactive iodine capture and identify economically viable materials, this study introduces a simple synthesis method for sp²C-COF material (NKCOF-41), which is characterized by high stability and low cost. NKCOF-41 features a large surface area, high porosity, and abundant nitrogen active sites, making it an ideal candidate for efficient iodine capture from air. The study investigates the adsorption performance of NKCOF-41 for I₂ under varying conditions, including temperature and iodine concentration. The results reveal that NKCOF-41 achieves a static saturation adsorption capacity of 4.4 g/g for I₂ at 75 ℃, and a dynamic adsorption capacity of 2.6 g/g for I₂ at approximately 400 ppm and 25 ℃. These performance metrics surpass those of traditional inorganic adsorbents and some previously reported COF adsorbents, highlighting the materials exceptional efficacy. Moreover, NKCOF-41 exhibits excellent cycling stability, retaining over 93% of its initial adsorption capacity after five adsorption-desorption cycles. Further characterization using X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy uncovers that the efficient adsorption of iodine by NKCOF-41 is primarily attributed to the Lewis acid-base interaction between the pyridine groups in the material’s framework and iodine molecules. This interaction significantly enhances the material’s affinity for iodine capture. In addition, NKCOF-41 is synthesized from low-cost monomers, using a straightforward method that can effectively reduce production costs while maintaining scalability for practical applications. This feature makes NKCOF-41 a promising candidate for large-scale deployment in radioactive iodine capture technologies. This study not only introduces a novel COF-based material for the efficient capture of gaseous iodine but also lays the groundwork for expanding the use of COF materials in nuclear environmental remediation. The findings offer new insights into material design and the potential application of COF in capturing and fixing radioactive iodine in air, contributing to the advancement of nuclear safety and environmental protection.