Sprayed hieratical biomimetic superhydrophilic-superhydrophobic surface for efficient fog harvesting

A desert beetle-inspired surface with alternating wettability has shown great potential in fog harvesting, which allows for the easy acquisition of fresh water. The fog harvesting mechanism has been deeply understood via the efforts of many scientists. Current studies focus on the effective fabrication of the fog harvesting material, and facile fabrication can greatly enhance its real application. In this work, using a simple spraying method and selective modification of mercaptan, we successfully fabricated a biomimetic surface with hybrid wettability consisting of a hydrophobic micro-particle/hydrophilic nano-particle hierarchical structure. When the mass ratio of Cu2O microparticles to ZrO2 nanoparticles in the spraying suspension was 8:1, the as-prepared hybrid sample had the highest fog collection efficiency of approximately 1707.25 mg·cm−2·h−1, which was two times higher than that of the superhydrophilic sample, showing prominent enhancement of the fog harvesting capacity. The special hierarchical structure can facilitate the water harvesting behaviour. The fabrication method has a low production cost and is facile, making the large-scale manufacture of fog harvesting collectors possible.