Local Femtosecond Pulsed Laser Decoating of Superhydrophobic Paper Coating for Enhanced Fog Harvesting Efficiency

Superhydrophobic paper has demonstrated significant potential for efficient water harvesting. Previous studies have indicated that the incorporation of pinning structures on superhydrophobic surfaces can enhance water collection efficiency. This study explores the feasibility of creating such pinning structures through femtosecond laser ablation of wax-based superhydrophobic coatings. Static contact angle measurements and the roll-off behavior of droplets on laser-treated surfaces are conducted to evaluate the effects of laser ablation. Additionally, fogging tests are performed to assess the water collection performance, revealing an improvement of above 10% in comparison to unmodified superhydrophobic paper without localized pinning structures. Notably, the laser ablation process minimally affects the load-bearing capacity of the paper, ensuring that its structural integrity is preserved. The ability to design laterally resolved pinning structures opens new possibilities for further optimization, such as the creation of flow paths, ultimately enhancing the overall efficiency of water harvesting systems.