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Fog Harvesting of a Bioinspired Nanocone-Decorated 3D Fiber Network

Li, Chang, Liu, Yufang, Gao, Chunlei, Li, Xin, Xing, Yan, Zheng, Yongmei
ACS applied materials & interfaces 2019 v.11 no.4 pp. 4507-4513
cacti and succulents, droplets, harvesting, hydrophilicity, irrigated farming, irrigation systems, surface area, water flow, zinc oxide
The bioinspired nanocone-decorated three-dimensional fiber network (N3D) can be fabricated, where an original 3D web is designed, inspired by some newest research findings of spider web, and it is decorated with hydrophilic zinc oxide (ZnO) nanocones inspired by cactus spine. Multilevel high specific surface area exposure on fiber together with the hydrophilic decoration enables it to be more attractive to water molecules. These nanocones can capture fog droplet, generate coalesced droplet, and accordingly make droplet transport efficient because of Laplace pressure difference. Especially, a novel mechanism revealed that after the nanocone-decorated fiber was wetted, that is, a water film formed and immediately broke up into droplets, owing to the force relating to Rayleigh instability. Consequent lower retention surface realizes the formation of fast continuous water flow, rather than the traditional intermittent course. Thus, outstanding fog-harvesting efficiency was achieved on N3D, for example, probably reaching 865.1 kg/m²/day, where the mass of collected water within 2 h can raise up to over 240 times higher than the weight of an original 3D web without nanocones. Such a bioinspired ZnO nanocone-decorated 3D fiber network (i.e., N3D) has potential application to harvest fog water for production or living, for example, water recondensation in cooling water towers and in agricultural irrigation systems, even in water-deficient countries.