Strong acid resistance from electrochemical deposition of WO3 on super‐hydrophobic CuO‐coated copper surface

In marine and industrial environments, salts and aggressive contaminants in water may cause corrosion and degradation, including acid corrosion and erosion. Super‐hydrophobic (SH) metal oxide films can keep surfaces dry by expelling water droplets. This inhibits corrosion. However, acid rain can dissolve the metal oxide films. Thus, it is necessary to protect SH films against acid erosion. In this work, a WO 3 film was added on top of CuO‐coated SH copper surface using electrochemical deposition. The composite SH CuO‐WO 3 film exhibited a strong acid resistance. After 48 h immersion in 0.2 N sulfuric acid, the film retained its nearly perfect micro‐nano structure with a static water contact angle of 160 ± 2°. After acid erosion, the corrosion rate in a 3.5% (w/w) NaCl solution was tested using potentiodynamic polarization curves. Its corrosion current density was found to be four orders of magnitude lower compared with CuO‐coated copper. This kind of acid resistant SH surfaces with much enhanced ability against atmospheric oxygen corrosion in the presence of salty water have potential applications in marine and other industrial environments.