Patterned Hybrid Surfaces for Efficient Dew Harvesting

Dew harvesting, minimally influenced by climate and geographical locations, is an ideal method for addressing water shortage problems. Superhydrophilic surfaces, characterized by their highest affinity for water, are particularly attractive for this purpose as they can attract more water molecules via condensation. However, a significant challenge arises from the high surface capillary force that impedes water from sliding down and being effectively collected. The resulting water film on the superhydrophilic surface tends to stay around the edge of the water collection surface, leading to evaporation loss and reduced collection efficacy. To overcome this problem, triangular patterns with low surface adhesion to water were introduced at the edge of superhydrophilic surfaces. This modification, achieved through a wet chemical method and masked oxygen plasma treatment, has significantly improved the efficiency of water collection. Results indicate that the hybrid surface reduced the time for the first water droplet to slide down by half and increased water collection efficiency by 78% compared to uniform superhydrophilic surfaces and by 536% compared to uniform superhydrophobic surfaces under a relative humidity of 55% with a temperature difference of 15 °C. The underlying principles were elucidated through computational simulations, and the mechanisms driving the enhancement in collection efficiency were explained.