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.

中文翻译：

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通过有机-无机整合的等离子体电解氧化在 AZ31 Mg 合金上实现高度耐腐蚀和光催化杂化涂层


本研究探讨了等离子体电解氧化 （PEO） 改性的 AZ31 Mg 合金的有机-无机杂化涂层的开发，以增强其耐腐蚀性和光催化性能。PEO 工艺通常会产生多孔氧化层，该层会通过允许腐蚀剂渗透基材来降低腐蚀保护。为了解决这一限制，苯并吡啶 （PHEN） 和 2-甲基咪唑 （2-IMD） 被掺入 PEO 表面，以在 Mg 合金上形成坚固的有机层。氢氧化钾 （KOH） 用于调节 pH 值，改善有机分子与 PEO 涂层之间的相互作用和溶解度。杂化涂层表现出独特的树枝状表面结构，有助于形成具有高耐腐蚀性和优异光催化活性的多功能涂层。镁合金上的 PEO-PHEN-2IMD 样品表现出优异的耐腐蚀性，具有最低的腐蚀电流密度 （I_corr） 为 1.92 × 10^-¹⁰ A/cm²，高腐蚀电位 （E_corr），最高顶层电阻 （R_top） 为 2.57 × 10⁶Ω·cm²，表明具有优异的阻隔性能。此外，该涂层在可见光下 30 分钟内实现了亚甲基蓝 （MB） 的完全 （100%） 降解。密度泛函理论 （DFT） 计算更深入地了解 PHEN、2-IMD 以及 Mg 合金和 MB 染料上的 PEO 层之间的键合机制和相互作用稳定性。这些发现证实了混合涂层在耐腐蚀性和光催化应用中的增强性能。