Coupling passive shield of in situ grown NiFe-LDH films with active corrosion inhibitor release of MBT@HOMS nanocontainers for durable self-healing anticorrosion coatings

Self-healing anticorrosion coatings based on inhibitor-loaded nanocontainers are often limited by rapid interfacial corrosion and inhibitor consumption after mechanical damage. Herein, a durable self-healing coating was designed by coupling a in situ grown NiFe-LDH interfacial film with pH-responsive MBT@HOMS nanocontainers. The NiFe-LDH film serves as a passive shielding interfacial and delay early interfacial corrosion, whereas MBT@HOMS releases MBT in response to corrosion-induced pH changes to provide active protection at damaged sites. The NiFe-LDH film was directly constructed at the organic coating/steel interface by galvanostatic Fe electrodeposition followed by corrosion-induced conversion. The pre-deposited Fe layer acted as both a sacrificial Fe source and a reactive template, enabling the formation of a continuous hierarchical LDH underlayer with a thickness of 1.91 μm. This micrometer-thick interfacial barrier served as a secondary shield after coating damage, increasing electrolyte diffusion tortuosity, delaying electrolyte access to the steel substrate, and suppressing early interfacial corrosion. Meanwhile, MBT@HOMS possessed a high surface area of 989.83 m 2 ·g −1 and an MBT loading of 16.3 wt%, with pH-triggered release of 91.4% under acidic conditions within 24 h. By The NiFe-LDH layer of composites coating shifted the impedance maximum from 20 to 30 days, reduced the average apparent degradation constant by 60.6%, and extended the characteristic degradation time from 20.0 to 50.8 days, indicating delayed the consumption of MBT, and prolonged self-healing protection. After 60 days in 3.5 wt% NaCl, the NiFe-LDH/MBT@HOMS-EP coating maintained an impedance modulus approximately 40 times higher than the single self-healing coating, demonstrating durable active/passive synergistic protection.