LAUSR

Abstract Modifier-free superhydrophobic surfaces have attracted much attention since their discovery due to the potential for applications. Although there is an emerging consensus that modifier-free structured hydrophilic surfaces can achieve superhydrophobic, how the surface morphology influence their wettability as well as why modifier-free structured surfaces can achieve superhydrophobic are lacking. In this work, we fabricated many Cu-Zn coatings with various surface morphologies on steel substrate by tuning electrodeposition parameters including the current density, the Zn2+/Cu2+ molar ratio, and the electrodeposition time. We found that these freshly prepared electrodeposited Cu-Zn coatings were superhydrophilic after dried. Interestingly, after storage in air for more than 60 days, these modifier-free hierarchical structured Cu-Zn coatings became superhydrophobic with the maximum water contact angle of 154.73° and the minimum sliding angle of ~6.5°. We experimentally demonstrated that both the hierarchical structure and the chemical composition (the formation of CuO-ZnO and the oxygen adsorption) contribute to the superhydrophobicity of the modifier-free Cu-Zn coating. Furthermore, this modifier-free superhydrophobic Cu-Zn coating presents excellent durability, self-cleaning, anti-corrosion, and anti-scaling properties.