Comparison of Superhydrophobicity, Anti-Corrosion, Anti-Icing, and Self-Cleaning Properties of Nickel and Cobalt Coatings Fabricated by one-Step Electrodeposition

In this research, superhydrophobic nickel and cobalt coatings with a hierarchical micro-nano structure were deposited on copper substrate by rapid one-step electrodeposition. The microstructure, wettability, corrosion resistance, self-cleaning and anti-icing properties of the coatings were evaluated using a scanning electron microscope (SEM), contact angle measurement, electrochemical impedance spectroscopy (EIS), alumina powder as contaminants and keeping at minus 15 °C, respectively. According to the obtained results, nickel coating with a higher contact angle of 172.3° delays the freezing of the droplet on the surface by 6 min more than the cobalt coating with a lower contact angle of 155.6°. The surface energies of both coatings were low enough to benefit from oleophobicity and for glycerol and ethylene glycol, both coatings had water contact angles higher than 120°. When the open circuit potentials were atablized in 3.5 wt.% NaCl solution, very high charge transfer resistances of 2370 and 756.3 kΩ.cm2 were recorded for nickel and cobalt coatings, respectively. After 16 days of immersion in saline solution, the contact angles were still in the hydrophobic range (128.7° and 98.6° for nickel and cobalt coatings, respectively). For cobalt coating with more appropriate surface microstructure and despite its lower water contact angle compared to nickel coating, better self-cleaning properties were observed.