Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan.
ACS Appl Mater Interfaces. 2021 Jul 28;13(29):35079-35085. doi: 10.1021/acsami.1c06432. Epub 2021 Jul 14.
Securing freshwater resources is a global issue for ensuring sustainable development. Fog harvesting is attracting great attention as a method to collect water without any energy input. Previous reports that were inspired by insects and plants have given insights such as the effectiveness of in-plane wettability and structural differences for droplet transport, which might enhance artificial water harvesting efficiency. However, further efforts to transfer droplets while maintaining performance are needed because droplet motion owing to these effects is limited to the in-plane direction. In this study, we report droplet transport between three-dimensional copper wire structures with nanostructured hydrophobic and superhydrophilic features. This mechanism enhanced the fog harvesting capability by more than 20% compared with the cumulative value of individual wires. In addition, the relationship between the droplet height and spacing of wires affected the performance. Our results show the importance of out-of-plane directional droplet transport from the wire surface assisted by differences in wire wettability, which minimizes limiting factors of fog harvesting including clogging and droplet shedding. Furthermore, the proposed arrangement reduces the overall system width compared with that of a two-dimensional arrangement while maintaining the amount of harvested water. These results provide a promising approach to designing large-scale and highly efficient fog harvesters.
保障淡水资源是确保可持续发展的全球性问题。雾水收集作为一种无需任何能源输入即可集水的方法，正引起人们的极大关注。受昆虫和植物启发的先前研究报告提供了一些见解，例如平面内润湿性和结构差异对液滴输运的有效性，这可能会提高人工集水效率。然而，需要进一步努力来转移液滴，同时保持性能，因为这些效应导致的液滴运动仅限于平面方向。在这项研究中，我们报告了具有纳米结构疏水性和超亲水性特征的三维铜丝结构之间的液滴传输。与单个电线的累积值相比，这种机制将雾水收集能力提高了 20%以上。此外，液滴高度和电线间距之间的关系影响了性能。我们的结果表明，由电线润湿性差异辅助的从电线表面进行的非平面定向液滴传输非常重要，这可以最小化雾水收集的限制因素，包括堵塞和液滴脱落。此外，与二维布置相比，所提出的布置减少了整个系统的宽度，同时保持了收集的水量。这些结果为设计大规模、高效的雾水收集器提供了一种很有前途的方法。
