Enhancing the photocatalytic performance and chemical durability of AZ31 magnesium alloy by incorporating two types of nanoparticles through plasma electrolytic oxidation

Abstract

The difficulty in achieving a balance between photocatalytic efficiency and chemical robustness has been a barrier to the broad use of MgO as a versatile material, mainly because of its restricted surface activity. To overcome this, a novel surface modification technique is proposed. It involves the integration of highly stable SnO₂ and WO₃ nanoparticles, which are known to enhance surface activity. This approach aims to achieve an optimal balance between efficiency and stability by finely tuning the structure-surface reactivity relationship. The technique utilizes a plasma electrolytic oxidation (PEO) method. In this method, both the AZ31 Mg alloy substrate and SnO₂/WO₃ precursors undergo simultaneous oxidation. This is induced by high-energy plasma generated through high voltage. The results demonstrate that this process yields a MgO layer with a homogeneous dispersion of SnO₂ and WO₃ nanoparticles, significantly enhancing its overall performance. Corrosion measurements demonstrated enhanced electrochemical stability against chloride ions. The dual incorporation resulted in a hybrid film exhibiting a corrosion current density value of 7.57 × 10⁻¹¹ A/cm² and a high outer layer resistance of 5.17 × 10⁷ Ω.cm². Additionally, the dual incorporation of SnO₂ and WO₃ nanoparticles enhances the photocatalytic activity of AZ31 Mg towards tetracycline degradation. This results in a photocatalytic efficiency of 89.54% within 2 h of exposure to visible light using the BA-W-Sn sample, which outperforms other samples. This integrated strategy enables the study to contribute significantly to expanding the practical applications of MgO-based materials. It does so by simultaneously enhancing their photocatalytic activity and chemical stability.