Superhydrophobic and anti-soiling properties of thin films from CeO_x nanoparticles

Cerium oxide (CeO_x) powders were synthesized via the co-precipitation method and deposited onto glass substrates using spin-coating. The transmittance spectra of the CeO_x films in the visible range (∼95 %) remained largely unchanged compared to the bare glass substrate, maintaining anti-reflective properties. The CeO_x films coated with 1-octadecene exhibited superhydrophobic behavior, achieving a water contact angle (WCA) exceeding 150° and self-cleaning properties at a sliding angle (SA) < 10°. The highest WCA values were observed for film thicknesses between 300–500 nm. Annealing at 350 °C, 450 °C, and 550 °C did not result in a noticeable change in WCA. Wettability studies in the acidity pH range of 2.1–10.4 indicated that solution pH and salt concentration had only a minor influence on WCA for pH > 2.1. Contact angles of ultrapure water and sea water on 1-octadecene-coated CeO_x films do not significantly differ. Compared to hydrophilic surfaces, the superhydrophobic films demonstrated remarkable self-cleaning capability, allowing water droplets to roll off effortlessly, carrying dust particles and effectively maintaining a clean surface.