All-day fresh water harvesting by microstructured hydrogel membranes

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 3.64kgm(-2) h(-1) 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 similar to 34Lm(-2) in an outdoor test, which demonstrates its potential for global water scarcity relief.

Automated summary

The hydrogel membrane developed combines solar steam water purification and fog collection, enabling all-day fresh water generation. In outdoor tests, it has demonstrated a daily fresh water yield of around 34 liters per square meter, showing potential for alleviating global water scarcity.