Zinc–cobalt bimetallic metal-organic framework (Zn/Co-MOF) nanoparticles as potent pH stimuli anti-corrosive agent for development of a self-healable epoxy composite coating

The impressive BET-surface area and the design versatility have made Z67(ZIF-67) MOF a potent nanomaterial for anti-corrosion applications. Despite excellent anti-corrosion features the Z67(ZIF-67) suffers poor stability in water media, making it improper for application in polymeric systems. One strategy to enhance the stability of Z67 is its structure modification via a mixed-metal organic framework approach. This study involved the synthesis of a series of Z67 nanoparticles through the incorporation of zinc cation (Zn) at different percentages. Specifically, three different compositions were synthesized: Zn10-Z67, Zn20-Z67, and Zn30-Z67 denoting the addition of 10 %, 20 %, and 30 % molar percent of Zn, respectively. FTIR, FE-SEM, XRD, TEM, ICP-OES, and XPS, as well as BET analyses, were conducted for the Zinc–Cobalt bimetallic MOF structure. Subsequently, the properties attributed to the particles' active and barrier anti-corrosion feature in solution (NaCl) as well as coating (epoxy) phases were investigated. The EIS test performed in the solution phase, after 72h of metal exposure to Zn30-Z67 containing saline media, revealed a 590 % and 30 % increase in total resistance, respectively, compared to the uninhibited sample. Due to the increased stability of Zn10-Z67 in a saline environment, the active corrosion inhibition of the scratched coating containing these particles was increased by approximately 140 % compared to the Z67-containing composite. The incorporation of zinc cations into the structure of Z67 has enhanced the stability and control release features in aqueous environments, thereby enhancing the barrier properties of the epoxy coating. The reduction rate of log|Z|0.01Hz of the Zn10-Z67/EPC was 9 % which was lower than that of the Neat EPC (epoxy coating) (24 %).