The corrosion resistance of magnesium alloys is a significant concern in industries seeking to use these materials for lightweight structures. Plasma electrolytic oxidation (PEO) is a process that forms a ceramic oxide film on Mg alloy surfaces, effectively enhancing their corrosion performance in the short term. In this regard, optimizing PEO process parameters is crucial for creating a stable oxide layer. An improved level of corrosion resistance is ensured by applying superhydrophobic coating (SHC) on top of the PEO layer to prevent moisture infiltration, creating air pockets on the surface. Various methods are employed to fabricate SHC on Mg alloys, including techniques like electrophoretic deposition (EPD), Hydrothermal (HT), dip, and spray coating. The synergistic combination of PEO and SHC coatings has demonstrated encouraging outcomes in enhancing the corrosion performance of Mg alloys. This study offers an extensive overview of recent progress in the preparation, characterization, and corrosion behavior of Mg alloys by employing PEO coatings and SHC treatment processes.

The crisis of excessive increase in CO₂ emissions has quickly become a serious issue and requires low-cost and bio-compatible solutions. The employee of membrane technology for CO₂ gas separation has garnered significant interest among researchers. However, this method encounters challenges related to selectivity and permeability. Therefore, modifying and reinforcing the polymer membranes to improve gas separation performance seems essential. Among the various methods for polymer membrane modification, modification with magnesium-based fillers to prepare a mixed matrix membrane (MMM) is considered an efficient method. Owing to magnesium metal’s low weight, low density, high strength, and good selectivity, magnesium-based materials (Mg-based materials) have more porosity, higher available surface area, more adsorption sites, lighter weight, and more gas absorption tendency than other fillers, which makes them an attractive choice for the preparation of gas separation MMMs. This research deals with the introduction of Mg-based materials, various methods of synthesis of Mg-based materials, different methods of introducing Mg-based materials into the membrane matrix, and their effect on the performance of MMMs in CO₂ gas separation applications. Therefore, this review can provide researchers with light horizons in using the high potential of Mg-based materials as efficient fillers in MMMs to achieve excellent permeability and selectivity and generally improve their performance in CO₂ gas separation applications.

This study presents a novel approach to improving the anticorrosive performance of AZ31 Mg alloy by exploiting the role of the hydration reaction to induce interactions between Quinolin-8-ol (8HQ) molecules and the porous MgO layer formed via plasma electrolytic oxidation (PEO). The AZ31 Mg alloy, initially coated with a PEO layer, underwent a dipping treatment in an ethanolic solution of 0.05 M 8HQ at 50 ℃ for 3 h. The results were compared with those from a different procedure where the PEO layer was subjected to a hydration reaction for 2 h at 90 ℃ before immersion in the 8HQ solution under the same conditions. The hydration treatment played a crucial role by converting MgO to Mg(OH)₂, significantly enhancing the surface reactivity. This transformation introduced hydroxyl groups (−OH) on the surface, which facilitated donor-acceptor interactions with the electron-accepting sites on 8HQ molecules. The calculated binding energy (E_binding) from DFT indicated that the interaction energy of 8HQ with Mg(OH)₂ was lower compared to 8HQ with MgO, suggesting easier adsorption of 8HQ molecules on the hydrated surface. This, combined with the increased number of active sites and enhanced surface area, allowed for extensive surface coverage by 8HQ, leading to the formation of a stable, flake-like protective layer that sealed the majority of pores on the PEO layer. DFT calculations further suggested that the hydration treatment provided multiple active sites, enabling effective contact with 8HQ and rapid electron transfer, creating ideal conditions for charge-transfer-induced physical and chemical bonding. This study shows that hydration and 8HQ treatments significantly enhance the corrosion resistance of Mg alloys, highlighting their potential for advanced anticorrosive coatings.

This study explores the development of an organic-inorganic hybrid coating to enhance the corrosion resistance and photocatalytic properties of AZ31 Mg alloy modified by plasma electrolytic oxidation (PEO). The PEO process typically generates a porous oxide layer, which can reduce corrosion protection by allowing corrosive agents to penetrate the substrate. To address this limitation, phenopyridine (PHEN) and 2-methylimidazole (2-IMD) were incorporated into the PEO surface to form a robust organic layer on the Mg alloy. Potassium hydroxide (KOH) was used to adjust the pH, improving the interaction and solubility between the organic molecules and the PEO coating. The hybrid coating exhibited unique twig-like surface structures that contributed to forming a multifunctional coating with high corrosion resistance and superior photocatalytic activity. The PEO-PHEN-2IMD sample on the Mg alloy demonstrated exceptional corrosion resistance, with the lowest corrosion current density (I_corr) of 1.92 × 10^-10 A/cm², a high corrosion potential (E_corr), and the highest top layer resistance (R_top) of 2.57 × 10⁶ Ω·cm², indicating excellent barrier properties. Additionally, the coating achieved complete (100%) degradation of methylene blue (MB) within 30 min under visible light. Density Functional Theory (DFT) calculations provide deeper insights into the bonding mechanisms and interaction stability between PHEN, 2-IMD, and the PEO layer on the Mg alloy and MB dye. These findings confirmed the enhanced performance of the hybrid coating in both corrosion resistance and photocatalytic applications.

The passivation of magnesium (Mg)-based alloys is an electrochemical behavior. The formation of a protective surface film results in passivation. The composition of this surface layer is influenced by the substrate alloy, which in turn affects the passive behavior. Recent studies have examined the composition of the surface film when Mg alloys undergo corrosion. Most of these studies have focused on the presence of Mg hydroxide (Mg(OH)₂) and MgO in the layer. However, a systematic examination of the impact of alloying elements on the stability of the passive layer is lacking. The essential question for developing a corrosion-resistant Mg-based alloy with passive protection is: which are the best and most efficient elements that can form a passive layer when alloyed with Mg? Passivity in a Mg alloy could be achieved by using a non-equilibrium technique to supersaturate the matrix phase with a high concentration of a strong passivating element. This review paper examines and explores the potential of creating a passive Mg-based alloy using metallurgical methods, like alloying and purification. Additionally, this paper explains key concepts about the passivity of Mg alloys and proposes possible methods to create a passive Mg alloy.

There has been considerable research into the use of powdered photocatalysts for their potential to remove a range of contaminants. However, the use of photocatalytic nanoparticles in real-world applications faces several challenges, including a tendency to clump together and issues with separating and reclaiming them. Of the various strategies for securing nanoparticles to a substrate, photocatalytic coatings have emerged as a promising solution to overcome the common limitations associated with powdered forms. Coatings produced through PEO have attracted considerable interest as versatile surface treatments. They hold the potential to improve the photocatalytic efficiency of magnesium alloys. Assessments of photocatalytic activity were carried out to examine the degradation of organic dyes when exposed to both visible light and UV. The findings show that the photocatalytic performance of PEO layers is improved, a feature that can be attributed to their distinct surface structure, composition, and properties related to light absorption. This research provides a deeper understanding of the photocatalytic properties of PEO layers applied to magnesium alloys. It underscores their potential use in environmental cleanup and energy transformation applications.

Advanced hybrid materials with unique properties are essential for addressing the demands of increasingly complex applications. Despite their importance, the self-assembly of layered double hydroxides (LDH) with metallic oxide nanoparticles and dicarboxylic acids is constrained by a limited understanding of the formation mechanisms and difficulties in evaluating their anticorrosive performance. In this study, we developed a novel anticorrosive system by intercalating CeNiLDH with a complex of vanadium pentoxide (V₂O₅) nanoparticles and (2E)-but-2-enedioic acid ((2E)-BDA) on a MgO layer created through plasma-electrolysis of AZ31 Mg alloy. This system was compared with LDH films intercalated with either V₂O₅ or (2E)-BDA alone. The intercalation of LDH with V₂O₅ and (2E)-BDA resulted in a flower-like structure, while modification with their complex led to a more compact, cloud-like formation. These cloud-like structures, driven by enhanced absorption and robust hydrogen bonding throughout the hierarchical network, effectively suppress corrosion by delaying the movement of corrosive anions. This was reflected in a polarization resistance of 1.51 × 10¹⁰ Ω·cm², which is approximately two orders of magnitude times higher than the resistance of the unmodified LDH film (3.41 × 10⁸ Ω·cm²). Additionally, the corrosion current density (i_corr) of the VOBDA sample showed a decrease by four orders of magnitude compared to the unmodified LDH sample, emphasizing the superior anticorrosive performance of this hybrid coating. Density functional theory (DFT) was used to elucidate the bonding and formation mechanisms between LDH and the inorganic-organic complex.

Modulating metal-organic framework’s (MOF) crystallinity and size using a polymer, in conjunction with a high surface area of layered double hydroxide, yields an effective strategy for concurrently enhancing the electrochemical and photocatalytic performance. In this study, we present the development of an optimized nanocomposite, denoted as 0.5PVP/ZIF-67, developed on AZ31 magnesium alloy, serving as an efficient and durable multifunctional coating. This novel strategy aims to enhance the overall performance of the porous coating through the integration of microarc oxidation (MAO), ZnFe LDH backbone, and ZIF-67 formation facilitated by the addition of polyvinylpyrrolidone (PVP), resulting in a three-dimensional, highly efficient, and multifunctional material. The incorporation of 0.5 g of PVP proved to be effective in the size modulation of ZIF-67, which formed a corrosion-resistant top layer, improving the total polarization resistance (R_p = 8.20 × 10⁸). The dual functionality exhibited by this hybrid architecture positions it as a promising candidate for mitigating environmental pollution, degrading 97.93 % of Rhodamine B dye in 45 min. Moreover, the sample displayed exceptional degradation efficiency (96.17 %) after 5 cycles. This study illuminates the potential of nanocomposites as electrochemically stable and photocatalytically active materials, laying the foundation for the advancements of next-generation multifunctional frameworks.

Corrosion is a pervasive phenomenon affecting materials across a multitude of scales, from the atomic to the macroscopic. This review paper presents a comprehensive examination of the methodologies employed in the analysis of magnesium corrosion, including electrochemical, non-electrochemical and analytical approaches, emphasizing the need for a diverse array of analytical tools to understand the complex interplay between corrosion, microstructure, and the dissolution mechanisms of magnesium alloys. The research showcases the utility of specific tools like SEM/EDS and SKPFM for targeted site analysis, while XPS and FTIR provide a broader perspective on specimen surfaces. The paper also discusses the value of in-situ analysis techniques, which allow for the real-time observation of corrosion processes, offering a dynamic view of the emergence and evolution of corrosion products. These in-situ methods stand in contrast to ex-situ analyses, which only permit post-experimental evaluation. By highlighting the capabilities of various analytical tools, from those that reveal surface layer details to those that probe deeper structures, and from those that detect primary elements to those that trace minute quantities of impurities, this study underscores the intricate nature of corrosion and the critical role of advanced analytical techniques in fostering a deeper understanding of material degradation. The findings advocate for the increased application of in-situ analysis in magnesium corrosion research, as it provides a more immediate and accurate depiction of corrosion dynamics, potentially leading to more effective corrosion prevention and control strategies.

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.