EIS analysis of hydrophobic and hydrophilic TiO2 film

Titanium oxide films were formed on metallic titanium substrates by employing a thermal treatment at 800 deg C under air atmosphere. Component and microstructure of the oxide films were characterized by XRD and SEM method. Water contact angles on titanium oxide film surface were measured in both dark and sunlight illumination condition. Corrosion tests were carried in seawater solution under different illuminate conditions. Electrochemical impedance spectroscopy (EIS) techniques were used to study the changes on TiO2 film. Results indicated that: hydrophilic TiO2 film suffered a severe photo-corrosion effect in seawater due to their semiconductor properties under sunlight condition, but the hydrophobic TiO2 film under dark condition exhibited a good corrosion resistance.