Green synthesis of natural nanocomposite with synergistically tunable sorption/desorption for solar-driven all-weather moisture harvesting

Sorption-based atmospheric water harvesting (SAWH) is a promising strategy for addressing freshwater scarcity in arid regions that extracts water vapor from the atmosphere and utilizes solar energy to drive desorption. Hygroscopic salts are commonly used to develop composite sorbents for SAWH with a high water uptake, but these salts often exhibit slow kinetics and high energy consumption for the desorption process. Herein, a natural composite hygroscopic hydrogel (NCHH) developed for sustainable and rapid SAWH, which achieved a 0.94 and 4.11 g/g high water uptake at humidity of 30% RH and 80% RH with fast sorption kinetics of ~0.47 and ~0.41 g∙g-1∙h-1, respectively, and outperformed most state-of-the-art hygroscopic hydrogels. To demonstrate its practical application, optimized NCHH was used to construct a prototype device for solar-driven SAWH, which demonstrated remarkable water production of about 1.33 L∙kg-1∙day-1 at a low humidity of 30% RH in an outdoor environment. Our study provides a prospective pathway for the synthesis of green and efficient composite sorbents to facilitate solar-driven all-weather SAWH.