A Hybrid Hydrogel with High Water Vapor Harvesting Capacity for Deployable Solar-Driven Atmospheric Water Generator

The Earth's atmosphere holds approximately 12,900 billion tons of fresh water and it distributes all over the world with fast replenishment. The atmospheric water harvesting is emerging as a promising strategy for clean water production in arid regions, land-locked, and remote communities. The water vapor sorbent is the key component for atmospheric water harvesting devices based on absorbing-releasing process. In this work, a flexible hybrid photothermal water sorbent composed of deliquescent salt and hydrogel was rationally fabricated. It possesses superior water sorption capacity even in low humidity air thanks to the deliquescent salt and it maintains a solid form after it sorbs a large amount of water owing to the hydrogel platform. The harvested water could be easily released under regular sunlight via the photothermal effect, and it can be directly reused without noticeable capacity fading. An "easy-to-assemble-at-household" prototype device with 35 g of the dry hydrogel was tested outdoors in field conditions and delivered 20 g of fresh water within 2.5 h under natural sunlight. It is estimated that the material cost of making such a device to supply minimum daily water consumption for an adult (i.e., 3 kg) is only $3.2 (USD). This type of atmospheric water generator (AWG) is cheap and affordable, perfectly works with a broad range of humidity, does not need any electricity, and thus is suitable especially for clean water production in remote areas.