Fabrication of Superhydrophobic Copper via Chemical Etching and Modification

Abstract

Biological superhydrophobic surfaces are relatively common in nature. Inspired by the superhydrophobic feature, plentiful materials with hydrophobic surfaces have been fabricated for various purposes such as anti-corrosion, anti-icing, self-cleaning, friction reduction, and oil-water separation. In the present work, we report a scalable, simple, and rapid method to fabricate superhydrophobic film on copper substrates via a simple route including a chemical etching step in sodium persulfate and sodium hydroxide solution and followed by a modification step in stearic acid solution. The effect of the etchants concentration as well as etching time was investigated exhaustively. From the obtained results it was found that when a copper plate was etched in an etching solution with low etchant concentration, the contact angle of copper was greatly influenced by etching time. In contrast, the etching time hardly affected the contact angle of the copper plate at the high concentration of the etchants. The superhydrophobic feature of the copper surface (with a contact angle larger than 150o) was only achieved in certain fabrication conditions. The superhydrophobic copper substrates demonstrated good anti-corrosion properties. The corrosion current density of superhydrophobic copper substrates was 85 times smaller than that of pristine ones when manufactured under optimal conditions. In addition, the as-prepared superhydrophobic copper mesh was used to successfully separate toluene from its aqueous mixture. The superhydrophobic copper has great potential for applications in oil-water separation and anti-corrosion in aqueous environments.