A Novel Nanoflower-like Zn–Cu Bimetallic Organic Framework: Enhanced Comprehensive Corrosion Resistance of Cu-MOF in Epoxy Resin Coatings

Copper-based metal-organic frameworks (Cu-MOFs) show great promise in corrosion protection due to their large specific surface area and inherent antibacterial properties. However, when applied to epoxy resin (EP) coatings, their tendency to agglomerate and the instability of the passive films formed during corrosion compromise the anticorrosion performance of the composite materials. To overcome these challenges, this study synthesized a series of zinc-copper bimetallic MOFs (Zn/Cu-MOFs) by incorporating zinc ions with similar ionic radii during the synthesis process. The surface morphology and ion release characteristics of the Zn/Cu-MOFs were comprehensively characterized using FE-SEM, XRD, FTIR, XPS, and ICP-OES. Subsequently, taking Zn₁₀/Cu-MOF (fabricated with a Zn²⁺-to-Cu²⁺ volume ratio of 1:9) as an example, the anticorrosion performance of the nanoparticles was assessed in both solution and coating systems. Remarkably, Zn₁₀/Cu-MOF nanoparticles achieved a corrosion inhibition efficiency of 89.7% for carbon steel after 24 h of immersion. Furthermore, electrochemical impedance spectroscopy (EIS) and salt spray tests on the coatings demonstrated that Zn₁₀/Cu-MOFs impart efficient corrosion resistance and self-healing ability to the EP matrix. After 40 days of immersion in 3.5 wt % NaCl solution, the Zn₁₀/Cu-MOF@EP coating exhibited a significantly higher low-frequency impedance modulus (|<i>Z</i>|_{0.01 Hz} ≈ 10⁸ Ω·cm²) compared to Cu-MOF@EP (∼10⁶ Ω·cm²) and pure EP (∼10⁵ Ω·cm²).