Sorption-tree with scalable hygroscopic adsorbent-leaves for water harvesting

Abstract

Sorption-based atmospheric water harvesting (SAWH), as a promising method of overcoming water scarcity in arid areas, has attracted increasing attention. Numerous excellent adsorbents have been developed to exercise their vast potential. However, in terms of device design, the conventional structure that stacks vast adsorbents into a plane not only worsens the material's heat and mass transfer properties but also impairs systemic solar utilization, both of which impede the practical application of SAWH. To break through this limitation, a three-dimensional sorption-tree with omnidirectional lighting has been promoted, inspired by natural trees. A scalable hygroscopic complex (RH 20–80%: 0.5–2.3 g g⁻¹) is developed as the adsorbent leaf to be decorated spatially on the sorption-tree. This design could boost integral sorption kinetics without sacrificing material capacity, while guaranteeing solar utilization efficiency in variable solar altitudes. In outdoor experiments, the sorption-tree's sorption capacity improved by 200–300%, and remarkable water productivity of up to ∼3200 ml per m² per day was achieved, which could fully satisfy the daily water demand of an adult.