Long-lasting corrosion protection of rusted steel via TA-driven chemical modification of LDH-diatomite and adsorption of 8-hydroxyquinoline

Steel corrosion in humid and saline environments severely threatens infrastructure service durability, while traditional coatings exhibit poor adhesion to rusted steel substrates. Herein, we fabricate a multifunctional anticorrosive filler via facile co-precipitation to in-situ grow Ni-Co layered double hydroxides (LDH) on diatomite (DE). Tannic acid (TA) acts dually as an efficient rust converter that converts iron oxides into stable iron tannate complexes, and a nucleation regulator for homogeneous LDH growth. The corrosion inhibitor 8-hydroxyquinoline (8-HQ) is anchored onto the LDH-DE skeleton via weak electrostatic and coordination interactions, achieving stimuli-responsive sustained release in corrosive media. When embedded into EP resin, the prepared TA/8-HQ@LDH-DE filler realizes hierarchical anticorrosion effects: physical barrier blocking ion penetration, in-situ rust conversion at steel coating interface, and stimuli-responsive inhibitor release to passivate active corrosion sites. Combined electrochemical impedance spectroscopy (EIS) tests and molecular dynamics simulations verify its outstanding anticorrosion performance on rusted Q235 steel. Notably, the TA/8-HQ@LDH-DE/EP coating containing 20 wt.% filler maintained the |Z|_0.01Hz value of 4.52 × 10⁸ Ω·cm² after 40 days of immersion, approximately two orders of magnitude higher than that of the EP coating. This work provides a scalable strategy for integrating passive barrier protection, interfacial rust stabilization, and active intelligent anticorrosion functions toward durable protection of rusted steel substrates.