High-yield solar-driven atmospheric water harvesting with ultra-high salt content composites encapsulated in porous membrane

Summary Sorption-based atmospheric water harvesting (SAWH) is recognized as a feasible and sustainable approach to address global water scarcity in arid regions. However, easy-to-prepare and inexpensive salt-based sorbents have stringent requirements referring to sorption duration and environmental humidity; otherwise, the leakage of salt solution can occur. Here, we develop a composite sorbent with remarkably high salt content of 80 wt % and without the risk of leakage by introducing a polytetrafluoroethylene membrane encapsulation method. The developed composite HSCC-E10 shows both fast sorption kinetics inherent to the matrix of composites and high absorption capacity of hygroscopic salt solutions, achieving ultra-high sorption capacity of 3.75 g/g, 2.83 g/g, and 1.47 g/g for 90%, 70%, and 30% relative humidity (RH), respectively. A lab-scale device is developed demonstrating 560 mL/m2 water yield under outdoor natural sunlight. The applicability of proposed sorbents could pave the road for future middle- or large-scale applications, such as vehicle-mounted and continuous SAWH.