Photocatalytic oxide coatings with inertly incorporated zeolite Y and ZnO on AZ31 magnesium alloy

Photocatalytically active oxide coatings were synthesized on AZ31 magnesium alloy using plasma electrolytic oxidation (PEO). Coatings were formed in a sodium phosphate-potassium hydroxide alkaline electrolyte with additions of Y-zeolite, ZnO, and their combination, and subsequently characterized in terms of morphology, composition, crystal structure, photoluminescence, and photocatalytic performance. The resulting layers exhibited typical porous morphology. Energy-dispersive spectroscopy confirmed significant Zn incorporation (up to 51 wt %) and the presence of Si and Al originating from zeolite, while X-ray diffraction verified preservation of zeolite crystallinity with inert incorporation of Y-type zeolite as well as ZnO particles. The presence of zeolite promoted thicker coatings and improved surface development, whereas ZnO incorporation introduced characteristic luminescence features associated with defect states. Photocatalytic performance, evaluated via methyl orange degradation, revealed that coatings containing both zeolite Y and ZnO achieved the highest efficiency ( 45 %), with significantly enhanced degradation after 6 h of UV irradiation compared to single-additive and reference coatings. The improved activity is attributed to the synergistic effect of increased surface area and enhanced charge carrier generation.