Superhydrophobic ceramic coatings enabled by phase-separated nanostructured composite TiO₂-Cu₂O thin films

By exploiting phase-separation in oxide materials, we present a simple and potentially low-cost approach to create exceptional superhydrophobicity in thin-film based coatings. By selecting the TiO₂-Cu₂O system and depositing through magnetron sputtering onto single crystal and metal templates, we demonstrate growth of nanostructured, chemically phase-segregated composite films. These coatings, after appropriate chemical surface modification, demonstrate a robust, non-wetting Cassie-Baxter state and yield an exceptional superhydrophobic performance, with water droplet contact angles reaching to ∼172̊ and sliding angles <1̊. As an added benefit, despite the photo-active nature of TiO₂, the chemically coated composite film surfaces display UV stability and retain superhydrophobic attributes even after exposure to UV (275 nm) radiation for an extended period of time. The present approach could benefit a variety of outdoor applications of superhydrophobic coatings, especially for those where exposure to extreme atmospheric conditions is required.