A facile strategy for the fabrication of a bioinspired hydrophilic-superhydrophobic patterned surface for highly efficient fog-harvesting

Fog water collection represents a meaningful effort in places where regular water sources, including surface water and ground water, are scarce. Inspired by the amazing fog water collection capability of the Stenocara beetles in the Namib Desert and based on the recent work in biomimetic water collection, this work reports a facile, easy-to-operate, and low-cost method for the fabrication of a hydrophilic-superhydrophobic patterned hybrid surface towards highly efficient fog water collection. The essence of the method is incorporating a (super)hydrophobically modified metal-based gauze onto the surface of a hydrophilic polystyrene (PS) flat sheet by a simple lab oven-based thermal pressing procedure. The produced hybrid patterned surfaces consisted of PS patches sitting within the holes of the metal gauzes. The method allows for easy control over the pattern's dimensions (e.g., patch size) by varying the gauze mesh size and the thermal pressing temperature, which is then translated into the easy optimization of the ultimate fog water collection efficiency. Given the low-cost and wide availability of both PS and the metal gauze, this method has great potential for scaling-up. The results showed that the hydrophilic-superhydrophobic patterned hybrid surfaces with a similar pattern size to the Stenocara beetles's back pattern produced a significantly higher fog collection efficiency than the uniformly (super)hydrophilic or (super)hydrophobic surfaces. This work contributes to the general effort in fabricating mixed wettability patterned surfaces for atmospheric water collection for direct use.