Efficient and Stable Fog Harvesting through Slippery-Superhydrophilic Patterned Surfaces: Pattern Regulation and Optimization

The scarcity of freshwater resources has emerged as a significant challenge for humanity. Fog harvesting, a process that converts atmospheric fog into readily accessible water, presents a promising solution. However, the surfaces currently developed for fog collection still face the problems of low efficiency and poor stability. To address these issues, this study designed a biomimetic hydrophobic slippery-superhydrophilic (SLIPS-SHPH) patterned surface. The surface was fabricated by a masked spray coating and lubricant infusion. By refining the pattern design, the wedge-shaped SHPH patterns, with a smaller size and an optimized total area ratio to SLIPS in a dispersed arrangement, were created. The SLIPS-SHPH integrates beetle- and cactus-spine-inspired SHPH patterns for fog accretion/droplet motion and pitcher-plant-mimicking SLIPS for droplet delivery/detachment. This synergy enables an efficient cycle of “fog capture-droplet transport-droplet release”, and achieves a water collection efficiency of 2462 mg·h–1·cm–2, 1.75 times that of the homogeneous hydrophobic surface. Notably, the SLIPS-SHPH patterned surface demonstrates excellent stability over a 120 h testing period owing to the stable water repellence of SLIPS. The research on the multilevel biomimetic strategies and pattern regulation provides a feasible way for efficient and sustainable fog collection.