Water harvesting method via a hybrid superwettable coating with superhydrophobic and superhydrophilic nanoparticles

Water collection gains increasing attention for harvesting atmospheric water in semi-arid deserts and inland areas. A new biomimetic method, inspired by the fog harvesting ability of hydrophobic-hydrophilic surfaces of Namib desert beetles, is presented in this study. It envisages a low-cost preparation (by the photocatalysis of titanium dioxide through ultraviolet irradiation) of a titanium dioxide-silicon dioxide hybrid superwettable surface combining superhydrophobic and superhydrophilic nanoparticles and exhibiting excellent water/fog collection properties. The surface wettability, condensation properties, water collection rate, and wetting stability of the product samples are investigated in detail. The results obtained strongly indicate that the proposed hybrid superwettable surface prepared by maskless photocatalysis enhances the water drop condensation and water collection characteristics, with very stable wettability. The best water collection and drop removal efficiency was experimentally determined at the ultraviolet irradiation time of 200 s. This work findings are considered instrumental in the further design and implementation of hybrid superhydrophobic-superhydrophilic surfaces for cost-efficient atmospheric water harvesting.