Abstract: In response to the serious challenge of global water scarcity, researchers are dedicated to developing highly efficient air water harvesting materials that possess the capability to efficiently capture and release water molecules. Under this background, metal-organic frameworks (MOFs) have emerged as prominent candidates among various materials for air water harvesting due to their high specific surface area, high porosity, excellent adsorption properties, and low desorption temperature. However, MOF materials are mostly used in powder form, which presents issues such as easy agglomeration, difficulty in molding, and long desorption times. Given that viscose fiber nonwoven materials resemble traditional fabrics in appearance and exhibit high flexibility, strength, hygroscopicity, air permeability, and porosity, they have become ideal carriers in the field of air water harvesting. Therefore, this study prepares a highly hygroscopic material, LiCl@MOF powder, using MOF-303 and lithium chloride (LiCl) as the base materials. By leveraging the adhesive properties of polydopamine (PDA), a bond is established between LiCl@MOF and viscose fiber nonwoven materials to produce LiCl@MOF-based nonwoven materials. 
For the purpose of achieving multiple cycles in the adsorption-desorption process of LiCl@MOF- based nonwoven materials, researchers used interfacial evaporation technology and chose viscose fiber nonwoven materials with photothermal conversion properties as the carrier. This enabled LiCl@MOF-based nonwoven materials to achieve efficient capture and release of water vapor. At night, the LiCl@MOF-based nonwoven materials leveraged their high porosity and hydrophilicity to adsorb and immobilize water vapor from the environment; while at daytime, the photothermal desorption function of the LiCl@MOF-based nonwoven material was used to convert the absorbed sunlight into thermal energy, accelerating the desorption and liquefaction of the water vapor adsorbed at night. This composite material not only enhanced the adsorption performance for water vapor in the air but also provided flexibility and cuttability to the air water harvesting material.
With the view of comprehensively evaluating the performance of LiCl@MOF-based nonwoven materials, tests were conducted on their morphology, crystal structure, composition, physical properties, and adsorption-desorption capabilities. The experimental results showed that LiCl@MOF was tightly adhered to the viscose fibers, and the crystal structure of MOF-303 was confirmed through XRD patterns. The physical property tests indicated that the wettability of the viscose fiber nonwoven material remained unchanged after being coupled with LiCl@MOF powder, while its mechanical properties, air permeability, and average pore size of the fibers decreased. Under dynamic conditions where the relative humidity (RH) increased from 30% to 95%, the water vapor adsorption capacity of the LiCl@MOF-based nonwoven material ranged from 0.3 to 5.06 g·g⁻¹. Under static conditions at an RH of 90%, its water vapor adsorption capacity was 4.9 g·g⁻¹. Meanwhile, when exposed to one sun intensity of irradiation, the material's temperature rapidly rose above 80 °C, and desorption was completed within 20 minutes. After multiple adsorption-desorption cycles, its adsorption performance was stabilized at 4.9 g·g-1 under static conditions, demonstrating its excellent cyclic stability.

Key words: MOF, LiCl, fiber-based nonwoven materials, interfacial evaporation technology, air water harvesting

摘要： 为解决金属有机框架（MOF）粉末在大气集水中存在的易团聚以及解吸时间长等问题，以粘胶非织造材料为载体、聚多巴胺为粘合剂，将LiCl@MOF粉末均匀地分散在粘胶非织造材料中，成功构筑了LiCl@MOF基非织造材料。对该材料的形貌和结构进行表征，分析其亲水性、力学性能、孔隙和透气率，并探究其在不同湿度条件下的动/静态水汽吸收动力学，以及在模拟太阳光照射下该材料的水汽解吸速率。结果表明：LiCl@MOF粉末均匀地负载到粘胶纤维表面；当相对湿度从30%动态提高到95%时，LiCl@MOF基非织造材料对水汽的吸附量从0.3 g/g提高至5.06 g/g，在相对湿度为90%的静态条件下吸附10 h后，其对水汽的吸附量从0 g/g提高到4.9 g/g；在一个太阳强度照射下，材料的表面温度迅速升至80 ℃以上，并在20 min内完成解吸。研究结果展示了LiCl@MOF基非织造材料在高效大气集水方面具有潜在应用价值。

关键词: 金属有机框架, 氯化锂, 纤维基非织造材料, 界面蒸发, 空气集水