Low Evaporation Enthalpy Ionic Covalent Organic Frameworks for Efficient Atmospheric Water Harvesting at Low Humidity
Zheng Shi1, Yu Guo1, Xiuyang Zou2, Jiamin Zhang1, Zhiwei Chen1, Mingqing Shan1, Zhixin Zhang1, Siyu Guo1(郭思宇)*, Feng Yan1(严锋)*
1Jiangsu Engineering Laboratory of Novel Functional Polymeric Materials, Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Suzhou Key Laboratory of Soft Material and New Energy, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123, P. R. China
2Jiangsu Engineering Research Center for Environmental FunctionalMaterials, School of Chemistry and Chemical Engineering, HuaiyinNormal University, Huaian, 223300, P. R. China
Angew. Chem. Int. Ed.2025, 64, e202420619
Abstract:Herein, we introduce a series of ionic covalent organic frameworks (iCOFs) with a focus on addressing the challenge of water collection at low relative humidity levels below 25 %. These iCOFs are characterized by numerous hydrophilic sites and high water stability, enabling efficient water vapor adsorption even at relatively low humidity levels. Through the use of various hygroscopic salt cations and precise control of ion concentration within the pores, the water state within the iCOFs pores can be effectively managed. Among the iCOFs, TB-COF-Li stands out with an impressive adsorption capacity of 0.24 g g−1 from 0 to 22 % RH. Notably, due to its ionic porous structure, TB-COF-Li exhibits a significantly lower enthalpy of evaporation, measured at 967.04 J g−1, compared to bulk water with an enthalpy of 2387.40 J g−1. Moreover, under simulated conditions of 1.5 solar intensity at 60 °C, the majority of the adsorbed water can be rapidly desorbed without the need for additional energy input. This efficient desorption process contributes to a high water collection rate of 0.092 g g−1 h−1 in the final atmospheric water harvesting device. The development of these iCOFs offers a promising and cost-effective solution for obtaining fresh water in arid regions.
Article information: //doi.org/10.1002/anie.202420619
