Visible Light-Activated Self-Recovery Hydrophobic CeO₂/Black TiO₂ Coating Prepared Using Air Plasma Spraying

Hydrophobic coatings are widely used in many areas from home to industry. However, the hydrophobicity can be easily degraded by adsorption of the atmospheric contaminations. In this study, a novel CeO2/black TiO2 hydrophobic coating with self-recovery capability is prepared using air plasma spraying without any chemical modification. The water contact angles (WCAs) of the coatings decreased after oleic acid contamination. Because of the presence of black TiO2, the composite coating has the photodegradation property under irradiation of visible light, and the part of the black TiO2 transforms to be superhydrophilic after irradiation for the generation of the surface oxygen vacancies. The oleic acid was decomposed and the WCAs changed depending on the volume percentage of the CeO2. The coating exhibits hydrophilicity when the volume percentage of the CeO2 is less than 60%, and hydrophobic when higher. After storage in a dark and clean environment, all the coatings can recover their hydrophobicity for the black TiO2 that returned back to its origin state. It is believed that this hydrophobic self-cleaning ceramic coating should have potential in engineering applications.