Triple-synergistic anti-corrosion nanocapsules: Empowering coatings with outstanding corrosion resistance

Abstract

Metal-organic frameworks (MOFs) provide significant benefits for loading metal corrosion inhibitors in anticorrosion on account of their high specific surface area and porous structure. Here, we present a novel BTA@Ce-ZIF-8 nanocapsule that exhibits pH-responsive behavior. Ce³⁺ and Zn²⁺ in the nanocapsule structure are common cathodic inhibitors, which can work in conjunction with the loaded metal corrosion inhibitor (benzotriazole) BTA to attain a triple anti-corrosion function. Q235 carbon steel is a common carbon structural steel, widely used in construction, bridges and other fields. The substrate used in this experiment is Q235 carbon steel. The incorporation of nanocapsules into the coating can impart self-repairing properties, as well as enhance its resistance to corrosion. The doping of Ce³⁺ proved effective in improving the poor dispersion of ZIF-8, as evidenced by scanning electron microscope images. Furthermore, BTA@Ce-ZIF-8 nanocapsules exhibited the highest rate of corrosion inhibitor release under acidic conditions, as demonstrated by UV tests. The BTA loading capacity was approximately 6.9 wt%. After 30 days of soaking, electrochemical impedance spectroscopy (EIS) measurements revealed that the impedance modulus for the 2 wt% BTA@Ce-ZIF-8/EP scratch coating reached 5.30 × 10³ Ω·cm², significantly higher than that of the pure EP. For scratch-free coatings with 2 wt% BTA@Ce-ZIF-8 nanocapsules, the impedance modulus remained above 10⁸ Ω·cm² after 50 days of immersion, showing remarkable self-repairing capabilities and corrosion resistance.