Multifunctional superhydrophobic copper mesh for efficient oil/water separation and fog collection

Exploration of functional materials for use in water treatment is one global requirement for protecting life and the environment. However, the state-of-the-art the materials used in oil/water separation and water harvesting still face challenges such as complicated processing steps, poor microstructure controllability and small-scale preparation. Here, a novel wire electrical discharge machining (WEDM) strategy is introduced to fabricate a functional copper mesh by cross machining both sides of the substrate, followed by a one-step low surface energy modification. The WEDM process makes the three-dimensional micro-nano structures can be well protected, and the low energy modification renders the surfaces superhydrophobic. The surfaces with micro-nano structures exhibited excellent superhydrophobicity (WCA≈158.8° and RA≈2°) and high durability towards mechanical abrasion (>100 cycles) and ultraviolet irradiation (>152° for 24 h). For various light/heavy oil/water mixtures, the separation efficiency of the meshes reached 98.1%, and the oil flux could reach 128.5 kL /(mm²·h). The superhydrophobic mesh could realize a highly efficient fog collection [12.0 L/(m²·h)], which was 390% and 830% higher than those treated by WEDM and the untreated copper plates, respectively. Therefore, we expect that the multifunctional superhydrophobic meshes may serve as a promising candidate for alleviating the water pollution and shortage.