All-day fresh water harvesting by microstructured hydrogel membranes.

Shi, Ye; Ilic, Ognjen; Atwater, Harry A; Greer, Julia R · Nat Commun · 2021

basic_science · Level V

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Abstract

Solar steam water purification and fog collection are two independent processes that could enable abundant fresh water generation. We developed a hydrogel membrane that contains hierarchical three-dimensional microstructures with high surface area that combines both functions and serves as an all-day fresh water harvester. At night, the hydrogel membrane efficiently captures fog droplets and directionally transports them to a storage vessel. During the daytime, it acts as an interfacial solar steam generator and achieves a high evaporation rate of 3.64 kg m<sup>-2</sup> h<sup>-1</sup> under 1 sun enabled by improved thermal/vapor flow management. With a homemade rooftop water harvesting system, this hydrogel membrane can produce fresh water with a daily yield of ~34 L m<sup>-2</sup> in an outdoor test, which demonstrates its potential for global water scarcity relief.