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Bioinspired Hierarchical Surfaces Fabricated by Femtosecond Laser and Hydrothermal Method for Water Harvesting

Lu, Jinlong, Ngo, Chi-Vinh, Singh, Subhash C., Yang, Jianjun, Xin, Wei, Yu, Zhi, Guo, Chunlei
Langmuir 2019 v.35 no.9 pp. 3562-3567
adhesion, condensation (phase transition), drinking water, dry environmental conditions, freshwater, hot water treatment, humidity, hydrophobicity, polydimethylsiloxane, water harvesting, water shortages, wettability
The world is facing a global issue of water scarcity where two-thirds of the population does not have access to safe drinking water. Water harvesting from the ambient environment has a potential equivalent to ∼10% of the fresh water available on the earth’s surface, but its efficiency requires a special control of surface morphology. We report a novel facile physicochemical hybrid method that combines femtosecond laser structuring with hydrothermal treatment to create a surface with a well-arranged hierarchical nanoneedle structures. Polydimethylsiloxane treatment of the thus-produced hierarchical structures nurtured superhydrophobic functionality with a very low water sliding angle (∼3°) and a high water adhesion ability. About 2.2 times higher water-collection efficiency was achieved using hierarchical structures over untreated flat Ti surfaces of the same area under a given experimental condition. The comparison of water-collection behavior with other samples showed that the improved efficiency is due to the structure, and wettability induced superior water attraction and removal ability. Moreover, a uniform water condensation under low humidity (28%) is achieved, which has potential applications in harvesting water from arid environments and in high-precision drop control.