Green Fabrication of Ultradurable Brass-Armored Superhydrophobic Surfaces: Application in Liquid Transport for Water–Air Systems

Abstract

An armored superhydrophobic surface was successfully fabricated on a brass mesh via an ultrasonically assisted etching process in dilute nitric acid and subsequent oxidation and growth of a hydrophobic infilling structure in an aqueous sodium laurate solution. The resultant robust hierarchical architecture comprises a microskeleton that supports a layer of Cu2O nanoparticles, interwoven with biomimetic nanosheet-based fillers. The surface exhibits considerable mechanical durability, maintaining superhydrophobicity under harsh mechanical stresses, including fingertip friction, knife scratch, load friction, and steel-wool abrasion. Enhanced chemical stability is established following ultrasonic etching in dilute nitric acid, oven heating for 180 days, and immersion in distilled water for 48 days. Fabrication of the microskeleton necessitates precise control of the differential Zn and Cu phase dissolution rates during etching. Practical application is demonstrated with a smart liquid transport device that integrates opposing superhydrophobic and superhydrophilic regions on a single brass tube, enabling the efficient and lossless transport of droplets in air (e.g., water) and underwater (e.g., oil) environments. The simplicity, controllability, low cost, and sustainable features of the proposed strategy make it a promising avenue for the development of advanced, robust, and intelligent liquid transport systems.