Parameters Influencing the Photocatalytic Activity of Suspension Sprayed ZnO-TiO₂ Coatings

Due to their promising photocatalytic properties under visible light irradiation, thermally sprayed ZnO-TiO₂ coatings are of interest as substitute for TiO₂ for various industrial applications, like hydrogen production via water splitting or the reduction of organic pollutants in water. Suspension spraying is an effective method to produce coatings in the binary ZnO-TiO₂ system to form Zn₂TiO₄ in-situ during the spraying process. Aqueous suspensions containing fine dispersed ZnO and TiO₂ particles are mixed at tailored composition and sprayed using the SHVOF and SPS spraying processes. Coatings with homogeneous distribution of elements and different surface structures and phase compositions are obtained. The phase composition is analyzed via XRD. UV-Vis spectroscopy measurements and photocatalytic tests of Rhodamin B degradation are performed. The potential to use appropriate binary suspension feedstock to produce ZnO-TiO₂-Zn₂TiO₄ coatings with different microstructures and photocatalytic properties is presented.