Durable superhydrophobic surface with hierarchical microstructures for efficient water collection

Abstract

Owing to the aggravation of water pollution and fresh water shortage, fabrication of functional materials with super-wettability surfaces for harvesting atmospheric water has gained widespread attention in recent years. In this paper, a superhydrophobic surface with combination of good robustness and efficient water-collecting performance was successfully fabricated via structuring multilevel microstructures. This hierarchically structured surface was prepared by photoetching, acid-etching, anodizing and fluoroalkylsilane modification treatments. The resultant surfaces exhibited great water repellency with the water contact angle (CA) of 173° and a low sliding angle (SA) of 1.5°, and showed good chemical stability both in air and severe acidic-alkaline environments. Furthermore, favorable water proofing property was still maintained after cyclical abrasion of the prepared superhydrophobic surface, with micrometer sized square frustum pillars to provide mechanical durability and the secondary bamboo shoots-like microstructure to provide water repellency. Water harvesting efficiency of this robust superhydrophobic surface was 5.3 g·cm − 2 ·h −1 , higher than those of the previous reported surfaces. This facilely fabricated superhydrophobic surface is expected to collect micro droplets from fog/mist environments so as to relieve the lack of water. • Micro-pillars and secondary bamboo shoots-like structures were fabricated. • The superhydrophobic surface shows good acid and alkali resistance. • As designed multi-level structures lead to well mechanical robustness. • Efficient water harvesting was realized via fast transportation of droplets.