Improving the photocatalytic performance of TiO₂ coating via the dual incorporation of MoO₂ and V₂O₅ by plasma electrolytic oxidation

In this study, the photocatalytic activity of TiO₂ coatings on pure titanium was significantly enhanced through the dual incorporation of MoO₂ and V₂O₅ particles. This enhancement was achieved by performing a series of plasma electrolytic oxidation (PEO) treatments in an alkaline-phosphate electrolyte, where Na₂MoO₄ and V₂O₅ nanoparticles were added either individually or in combination. The PEO process was carried out at a current density of 100 mA/cm² for 5 min. The results revealed notable changes in the surface morphology of the TiO₂ coatings, with a slight increase in porosity and a decrease in pore size observed in the sample treated with MoO₄²⁻ ions. The incorporation of V₂O₅ nanoparticles led to a further increase in porosity while maintaining a comparable pore size to the sample treated with MoO₄²⁻ ions. Interestingly, the simultaneous addition of both MoO₄²⁻ ions and V₂O₅ nanoparticles resulted in the smallest pore size and reduced porosity, forming a structure that could prove beneficial for photocatalytic applications. The compositional analysis confirmed the successful incorporation of MoO₂ and V₂O₅ into the TiO₂ matrix via electrochemical decomposition and electrophoresis mechanisms. Photocatalytic performance was evaluated through the degradation of methylene blue (MB) under visible light. The results demonstrated that the combined incorporation of MoO₂ and V₂O₅ significantly improved the degradation efficiency compared to TiO₂ coatings prepared without these additives. Notably, the TiO₂ coating with both additives achieved 99.9 % degradation of MB within 80 min, indicating enhanced charge separation and photocatalytic efficiency. This study highlights the potential of dual additive incorporation to improve the functional properties of TiO₂ coatings, making them suitable for advanced environmental and industrial applications.