Efficient water-collection hybrid surface optimized through combination-hole arrangement and diversion groove structure design

Abstract

Here, we have employed a simple and efficient immersion method to create a superhydrophobic coating on a stainless-steel substrate. Subsequently, we use laser equipment to process hydrophilic conical holes in specific areas of the superhydrophobic stainless steel surface, constructing a hydrophilic-superhydrophobic hybrid surface for water collection. By optimizing the combination of hydrophilic holes of different sizes and introducing continuous hydrophilic diversion grooves, we have maximized the water collection efficiency of the hybrid surface. The study reveals that introducing small holes in the upper-row can accelerate the water collection frequency and increase the water collection amount of the combination-hole hybrid surface. The droplet collection frequency and transport speed are superior to those of a single-hole hybrid surface. However, when the collected droplets reach the edge of the sample, there is a common phenomenon where larger droplets hang on the edge of the hydrophilic pattern without falling, significantly reducing the water collection efficiency of the hybrid surface. The introduction of continuous hydrophilic diversion grooves can act as drainage, effectively solving the “pinning” phenomenon of droplets at the edge of the sample, further enhancing the water collection efficiency of the hybrid surface to 2326.5 mg cm⁻² h⁻¹, approximately 1.58 times higher than before the introduction. This unique surface design, combining discrete hydrophilic holes and continuous hydrophilic diversion grooves, provides a new approach for water collection on hybrid surfaces. Its superior water collection capability also offers a potential solution to the problem of freshwater scarcity.