Hybrid Nanofiber-Based Atmospheric Water Harvesters: Sunlight-Driven Operation in Low-Humidity and Low-Illumination Environments
Yi Hu, Yu Chen, Jianing Xu, Wanli Cheng, Yi Lu, Guangping Han, Orlando J. Rojas
Abstract
Aerogels incorporating hygroscopic salts have been widely explored for atmospheric water harvesting (AWH). However, the scalability of these sorbents remains limited due to their reliance on energy-intensive and time-consuming drying methods such as lyophilization or supercritical drying. Here, we present a simple and scalable approach to drying hydrogels with desirable AWH properties using a freezing process followed by solvent exchange and thawing at room temperature. Our system consists of cellulose and silica nanofibers, forming hybrid xerogels with ultralow density (10.86 ± 0.32 mg cm –3 ), high specific surface area (104.22 m 2 g –1 ), excellent water stability, and mechanical strength. By incorporating carbon-based photothermal materials and lithium chloride as a hygroscopic salt, the xerogels achieve exceptional water uptake capacities ranging from 0.90 to 3.21 g g –1 across a relative humidity (RH) range from 15 to 75%. Under natural sunlight, the AWH xerogel produces water at a rate of 1.17 g g –1 day –1 . These results highlight a sustainable and scalable AWH strategy, leveraging ambient-dried xerogels as an energy-efficient solution to mitigate water scarcity.