3D Printed Cellulose Nanofiber Aerogel Scaffold with Hierarchical Porous Structures for Fast Solar-driven Atmospheric Water Harvesting.

Hygroscopic salt-based composite sorbents are considered ideal candidates for solar-driven atmospheric water harvesting (AWH). The primary obstacle for the sorbents lies in exposing more hygroscopic active sites to the surrounding air while preventing salt leakage. Herein, we construct a hierarchical structured scaffold by integrating cellulose nanofiber (CNF) and lithium chloride (LiCl) as building blocks through 3D printing combined with freeze-drying. The milli/micron multiscale pores can effectively confine LiCl and simultaneously provide more exposed active area for water sorption and release, accelerating both water sorption and evaporation kinetics of the 3D printed structure. Compared to the conventional freeze-dried aerogel, the 3D printed scaffold exhibits a water sorption rate that is greater than 1.6 times, along with a water release rate that exceeds 2.4 times. An array of bilayer scaffolds is demonstrated, which can produce 0.63 g g -1 day -1 of water outdoors under natural sunlight. Our work provides a sustainable strategy for collecting freshwater from atmosphere. This article is protected by copyright. All rights reserved.