Fabrication of superhydrophobic copper sulfide film for corrosion protection of copper

Abstract A copper sulfide (digenite phase, Cu 9 S 5 ) film composed of hierarchical microprotrusions was fabricated for corrosion protection of the underlying Cu substrate. The copper sulfide microprotrusions follow a heterogeneous nucleation, growth and aggregation mechanism. After hydrophobization with stearic acid, the film exhibits a water contact angle of 163° and a sliding angle of ~ 2°, and shows enhanced corrosion resistance. The mechanism of corrosion protection is clarified according to the proposed equivalent circuits, which show that the superhydrophobic film behaves as an effective barrier and largely separates the Cu substrate from the corrosive solution. The film exhibits good chemical stability against acidic or basic solutions due to the chemical inertness of copper sulfide. It shows good adhesion to the substrate and maintains its hydrophobic property after abrasion test.