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

Zhu, Penghui; Yu, Zhengyang; Sun, Hao; Zheng, Dingyuan; Zheng, Yi; Qian, Yangyang; Wei, Yuan; Lee, Jongho et al. · Adv Mater · 2024

basic_science · Level V

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Abstract

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