Fabrication of a Hierarchical Bioinspired Super-Contrast Wettability Surface for Enhanced Atmospheric Water Collection

With a growing population and severe water pollution, worldwide water scarcity has become a serious problem. In this context, collecting water from the atmosphere is regarded as a promising route to alleviate the global water shortage. Inspired by indocalamus leaves, desert beetle backs and cactus spines, we report a hierarchical bioinspired super-contrast wettability surface (BSCWS) fabricated on Ti-6Al-4V alloy via nanosecond laser selective processing and chemical modification. The BSCWS exhibits extreme contrast wettability with superhydrophobic regions (water contact angle: 167.4 ± 1.1°) and superhydrophilic regions (water contact angle: 0°). The mechanism underlying the extreme wettability transition was elucidated through systematic chemical composition analysis. Furthermore, a novel type of three-level BSCWS was designed, which can realize large-area water collection, directional transport and centralized storage. Under 100% relative humidity, the three-level BSCWS achieves a collection efficiency of 203.1 ± 10.8 g/m2·h, which is 1.3, 3.3, 5.6 and 8.0 times higher than those of the two-level BSCWS, superhydrophilic, superhydrophobic and smooth surfaces. A dual Laplace pressure-driven mechanism is proposed to explain the enhanced atmospheric water collection performance. This work provides a scalable and light-weight strategy for high-efficiency atmospheric water collection.