Oxygen vacancy induced superhydrophobicity of air plasma spraying deposited Y₂O₃ coatings

Air plasma spraying (APS) is widely used for preparing superhydrophobic rare earth oxide (SH-REO) coatings due to its advantages of capable for large-scale and fast deployment with low cost. However, the origin of the superhydrophobicity remains unclear, which has impeded the design and development of robust APS-deposited SH-REO coatings. In this work, by studying APS-deposited superhydrophobic yttrium oxide (SH-Y₂O₃) coatings, we found a close correlation between oxygen vacancy and surface adsorbed species. Our results suggest that oxygen vacancy introduced during APS makes the Y₂O₃ surface liable to the adsorption of nonpolarized, hydrocarbon molecules, which contributes to a low-energy surface. Therefore, we showed the crucial role of oxygen vacancy in the acquirement of reliable SH-REO coatings.