Laser-textured biomimetic copper leaf with structural-wettability dual gradient for efficient fog harvesting

Water collection has gradually become research hot topic owing to its potential for alleviating water shortages in arid areas. To date, numerous artificial materials with hierarchical structure have been fabricated to improve water-collecting efficiency. Here, a multi-bioinspired fog-harvesting artificial Cu-Leaf, deriving from Leaf skeletons, Namib desert beetle, and Cactus spines, is fabricated by ultrafast laser selective ablation, chemical etching and chemical vapor deposition, which achieve efficient water-collecting by combining fog capture, droplet growing and directional transportation together. The four-level wedge-shaped tracks of Cu-Leaf skeleton and its wetting property were finely adjusted and their correlations with the fog-harvesting capability were systematically studied. Force analysis related to fog capture, droplet growing and the droplet directional transportation on the hydrophobic/hydrophilic patterned skeleton surfaces have been highlighted. The optimal biomimetic Cu-Leaf performed superior fog-harvesting property with harvesting rate of 544.03 mg/h cm2, which is 2.5 times that of the original Cu sheet. Moreover, we designed an integrated fog-harvesting device (FHD) that could realize the dynamic fog-harvesting and efficient water storage. Therefore, this work enhances the understanding of the fundamental research and provides valuable strategy for design and preparation of sustainable and efficient fog harvesting systems.