Enhancement of water collection efficiency by optimizing hole size and ratio of hydrophilic-superhydrophobic area on hybrid surfaces

The scarcity of freshwater resources has had a significant impact on human life and wildlife survival. Fog harvesting has emerged as one of the most effective solutions to alleviate water scarcity in arid areas. At present, researchers have focused on optimizing hybrid surface designs to capture fog from the air and convert it into water droplets. Here, we prepared a hybrid surface for fog harvesting by a combination of chemical etching and surface modification with mechanical drilling. By adjusting the hole size and the ratio of hydrophilic-superhydrophobic area of the hybrid surfaces, the water collection efficiency was improved. The results indicated that the hole size affected the critical size of sliding water droplets, and the ratio of hydrophilic-superhydrophobic area affected the water droplet sliding speed and water collection frequency, thereby affecting the water collection efficiency per unit time. Therefore, by matching a specific hole size and ratio of hydrophilic-superhydrophobic area, the water collection volume and mobility of water droplets on the hybrid surfaces reached a dynamic equilibrium, achieving the optimal water collection efficiency. When the hole size was 1.0 mm, and the ratio of hydrophilic-superhydrophobic area was 1:4, the highest water collection rate was 805 mg/cm2/h, and the water collection efficiency was 17.5 %. By optimizing the hole size and the ratio of hydrophilic-superhydrophobic area, the water collection efficiency of the hybrid surface was maximized. This lays a solid foundation for promoting the practical applications of hybrid surfaces for fog harvesting.