Solar-assisted smart nanofibrous membranes for atmospheric water harvesting

The enormous reserves of atmospheric freshwater have been explored as a sustainable water resource to meet water needs in arid areas with suitable water sorbent material. Herein, we demonstrate a free-standing and super water-absorbing hydrogel nanofibrous membrane that turns airborne water vapor into potable water, even at low humidity levels. The hygroscopic behavior of LiCl in the thermo-responsive polymeric network enables the dried nanofiber membrane to initiate moisture sorption, and the nanofiber membrane turns into a soft hydrogel as it swells during water sorption. This hydrogel nanofiber exhibits record water uptake of 96%, 176%, and 273% at relative humidity values of 30%, 60%, and 80%, respectively. Due to the interesting hydrophilic-to-hydrophobic conformational change from temperature responsiveness of the nanofiber, liquid water rapidly oozes out with minimal energy consumption under solar irradiation. A lightweight, flexible, and scalable nanofiber membrane is highly desirable for efficient water harvesting, dehumidification, and evaporative cooling with low-grade energy consumption.