Facile Fabrication of a Superhydrophobic Cu Surface via a Selective Etching of High-Energy Facets

The Cu surface with a dual-scale roughness has been prepared via a facile solution-phase etching route by the H2O2/HCl etchants. The selective etching of the high-energy {110} facets occurs at an ultralow rate of the redox etching reaction. The resultant surface is composed of many polyhedral microprotrusions and nanomastoids on the microprotrusions, exhibiting the binary micro/nanostructures. After hydrophobization, the resultant surface exhibits a water contact angle of 170 degrees and a sliding angle of similar to 2.8 for a 5 mu L droplet. The combination of the dual-scale roughness and the low surface energy of the adsorbed stearic acid accounts for the superhydrophobicity. Such a superhydrophobic Cu surface has an excellent nonsticking behavior and anticorrosion against electrolyte solution. It also keeps its superhydrophobic ability after a long-time ultrasonication or abrasion test. Our work may shed light on the selective etching of other metal surfaces to create designed dual-scale roughness for superhydrophobicity.