Water collection has been extensively researched due to its potential for mitigating the water scarcity in arid and semiarid regions. Numerous structures mimicking the fog-harvesting strategy of organisms have been fabricated for improving water-collecting efficiency. In this contribution, we demonstrate four-level wedge-shaped tracks inspired by leaf vein for enhancing directional water collection. Superhydrophilic Cu(OH)2 nanowires are introduced and prepared on flexible hydrophobic polyethylene terephthalate (PET) substrates by alkali-assisted surface oxidation at room temperature. They provide abundant capillary paths for promoting droplet absorption and forming water film tracks. Then, the hierarchical wedge-shaped tracks enable the water to be transported to a certain accumulation region spontaneously owing to the continuous Young-Laplace pressure difference. As a result, the four-level wedge-shaped tracks on PET substrate achieve the highest water-collecting efficiency, increasing by nearly 1150 and 510% compared to the bare PET and Cu(OH)2 nanowires on PET, respectively. After being bent for 105 cycles at a radius of 10 mm, the samples can still preserve high efficiency, indicating that the synthetic structures possess outstanding durability. Our approach provides a novel strategy for water collection and paves ways for directional liquid transportation and microfluidic devices.
Keywords: Cu(OH)2 nanowires; directional water collection; flexible substrate; leaf vein-inspired; wedge-shaped tracks.