Design synthesis and synergistic anticorrosion performance of ZIF-8/NiAl LDH heterojunction nanocontainers

This study introduces a novel relay and synergistic anti-corrosion mechanisms by constructing an active anticorrosive coating with nanocontainers through the combination of zinc-based zeolitic imidazolate framework materials (ZIF-8) and layered double hydroxides loaded with molybdate anions (MoO₄²⁻ LDHs). The incorporation of ZIF-8 provided the material with abundant surface nano-micropores, enhancing its adsorption capacity for corrosive ions such as OH⁻ and Cl⁻. Simultaneously, this adsorption enabled the ZIF-8-loaded NiAl-MoO₄²⁻ LDH to receive signals induced by Cl⁻ stimulation or pH changes. After receiving the signals, the corrosion inhibitor MoO₄²⁻ encapsulated within the NiAl-MoO₄²⁻ LDH was released responsively and exchanged with Cl⁻. The released MoO₄²⁻ from nanocontainers adsorbed onto localized corrosion sites, forming a passivation film, thereby blocking the diffusion path of Cl⁻. Additionally, this study demonstrated that the self-assembly of ZIF-8 effectively reduced the hydrophilicity of LDH and enhanced the resistance of coating to permeability. Through supramolecular interactions between LDH hydroxyl groups, metal-organic framework (MOF) functional groups and organic epoxy resin, the cross-linking of the coating and the interfacial compatibility of the materials were significantly improved. The Z-type heterojunction composed of nickel-based LDH and metal organic frameworks not only increased the specific surface area and capacitance performance but also provided photo-induced cathodic protection for metal substrates with matched bandgaps. The experimental results showed that the impedance properties of the ZIF-8/NiAl-MoO₄²⁻ LDH coatings were 28.43 times of pure epoxy after 168 h. This work can provide new insights and assistance for the study of anti-corrosion mechanisms.