A Pragmatic Device Based on a Double‐Sided Functional Structure for Efficient Water Harvesting

Water collection from fog has received much attention to meet the challenges of scarcity of clean drinking water in desert and arid regions. Currently, solar‐thermal technology is being used as an efficient, sustainable, and low‐cost method for water desalination to produce clean water. To collect the clean water, in recent years, most researchers have designed the structure of water collection surfaces. However, the heat released during the liquefaction process of droplets has an adverse effect on the condensation of droplets, and thus affecting the water collection efficiency. Here, in order to improve water collection efficiency, a radiative cooling layer is introduced on the back of the collection surface to dissipate the heat released during droplet liquefaction. The radiative cooling layer, consisting of poly(vinylidene fluoride‐co‐hexafluoropropene) embedded with SiO 2 and CaMoO 4 nanoparticles, can theoretically cool 18.1 °C below the ambient temperature in the daytime. With the addition of cooling coating on the back of the water collection surface, the water harvesting efficiency can be increased by 43–52%. The developed water harvesting device may provide a new pathway to the efficient collection of fresh water.