Wettability contrast on the surface of CuO nanostructures for highly efficient fog harvesting

Abstract

Fog collection can provide a sustainable and efficient method for solving the shortage of water resources. In this article, CuO nanostructures were designed and synthesized on the Cu mesh by a one-step oxidation method and used to collect water from fog. Their morphology and surface wettability are characterized through scanning electron microscopy and dynamic contact angle measuring device, while the process of fog collection is investigated by a high-speed camera. The fog collection efficiency depends on the microstructure of the sample surface, which could be well controlled by adjusting the reaction temperature. Compared with CuO nanoneedles and CuO nanowire clusters, CuO nanosheets promote the rapid falling of liquid droplets, improving the fog harvesting efficiency, which can achieve 3168 mg/cm2 within 120 s. CuO nanosheets have ultra-low adhesion due to high roughness and high air restraint ability, accelerating the transport of water droplets and reducing the re-evaporation of water droplets.