Bio-inspired 3D-printed TPU/LiCl hierarchical porous cones for high-performance atmospheric water harvesting

Abstract

Global water scarcity poses a critical challenge, particularly in arid and semi-arid regions where access to fresh water is limited. Atmospheric water harvesting (AWH) is an innovative solution for capturing moisture and converting it into usable water. Owing to their absorption capacity and cost-effectiveness, hygroscopic salts, such as lithium chloride (LiCl), are of great importance for AWH; yet their practical applications are impeded by issues such as clumping and leakage. To address these challenges, this study combines thermoplastic polyurethane with LiCl using selective laser sintering 3D printing technology to fabricate bio-inspired hierarchical porous cones (HPCs). LiCl particles are embedded in polymeric scaffolds, exposing more active areas for water sorption and release, which favors both AWH and further water evaporation kinetics of the 3D-printed object. The as-prepared HPCs demonstrate a moisture absorption as high as 2.65 g g⁻¹ at 80% relative humidity, exhibiting exceptional water-harvesting performance. The 3D-printed objects maintain stable performances over multiple absorption–release cycles, validating their effectiveness under real-world conditions. A 3D-printed HPC array has been demonstrated, which can produce 1.89 kg kg⁻¹ day⁻¹ of AWH under natural sunlight. This work provides insights into the development of efficient AWH systems and lays the groundwork for future innovations in sustainable water sourcing.