Plasma electrolytic oxidation (PEO) is an electrochemical process recognized as one of the most effective techniques for functional coatings. In this process, a high voltage is applied to the electrolyte, resulting in a plasma discharge on the surface of a light metal alloy substrate, forming a hard and dense ceramic coating. We incorporated several powders of well-known semiconductor photocatalysts, including TiO₂-graphene, 2D-WO₃, 2D-MoO₃, and 2D-Bi₂WO₆, as additives to the electrolyte. Our objective was to produce plates with coatings of the aforementioned 2D photocatalysts, which show high potential for degrading various organic pollutants in water.

The photocatalysis process we utilized is based on reactions that occur on the coating surfaces in the presence of water and sunlight. Specifically, under UV-VIS light, electrons and holes are photogenerated in the semiconductor PEO-layer. These, in turn, react with dissolved oxygen, hydroxyl ions, and water to form reactive oxygen species, which effectively degrade pollutants into simpler molecules.

We tested coatings with homogeneous, single layers of photocatalysts as well as combinations forming multilayer structures. As a result, the obtained layers demonstrated high photocatalytic activity against organic compounds under UV-VIS irradiation. Our research focused on preparing highly porous coatings composed of 2D structures with enhanced photocatalytic properties, suitable for easy application in water remediation.