Superhydrophobic and photocatalytic self-cleaning surfaces by atmospheric pressure plasma jet deposited hydroxyapatite, titanium-dioxide silicone-like multilayers

The development of superhydrophobic coatings with remarkable water repellence is a prominent area of research in material engineering and coating industries. These coatings address various application areas by offering characteristics such as corrosion resistance, drag reduction, anti-icing, anti-fogging, and self-cleaning properties. To achieve excellent water repellence, both suitable surface chemistry with nonpolar functional groups and micro-nano structured rough surfaces are necessary. This study focuses on the fabrication of a hierarchical structured powder layer composed of hydroxyapatite microparticles and titanium dioxide nanoparticles, deposited by simple and easily scalable dip coating process on silicon wafers and stabilized by a silicone-like top layer deposited by atmospheric pressure plasma jet. The structure, chemistry, and self-cleaning ability of this coating system in terms of superhydrophobicity and photocatalytic activity are investigated using various analytical techniques, including white light interferometry, scanning electron microscopy, Fourier transform infrared spectroscopy, water contact angle measurements, and optical transmission spectroscopy. Results show that the multilayer film exhibits superhydrophobic properties with water contact angles above 150°, as well as photocatalytic activity and scratch and wear resistance. Such self-cleaning surfaces have potential applications in anti-corrosion, -icing, -fouling, and medical engineering fields. • Superhydrophobic coatings for corrosion resistance, drag reduction, anti-icing, anti-fogging, self-cleaning properties • Unique hierarchical coating structure with powder layer composed of hydroxyapatite microparticles and titanium dioxide nanoparticles • Scalable fabrication process dip coating followed by atmospheric pressure plasma jet deposition • Photocatalytic activity • Scratch and wear resistance