pH−Responsive Graphene Oxide−Based 2D/3D Composite for Enhancing Anti−Corrosion Properties of Epoxy Coating

The functionalized graphene oxide (GO)-based composites as fillers added into organic coatings are desired for realizing the longstanding corrosion protection of carbon steel. Here, the pH-responsive two-dimensional/three-dimensional (2D/3D) GO-based composite (ZIF–90–AAP/GO) was developed by environmentally friendly corrosion inhibitor 4-aminoantipyrine (AAP) anchored on the in situ growth of zeolite imidazolate framework–90 (ZIF–90) on the GO surface (ZIF–90/GO) through the Schiff base reaction. The active filler (ZIF–90–AAP/GO) was incorporated into an epoxy coating (EP) to obtain a high-performance self-healing coating on the surface of carbon steel. ZIF–90–AAP can greatly improve dispersion and compatibility of GO in EP. The low-frequency impedance modulus of ZIF–90–AAP/GO–EP can still reach up to 1.35 × 1010 Ω⋅cm2 after 40 days, which is about three orders of magnitude higher than that of the EP containing GO (GO–EP) relying on its passive and active corrosion protection. Meanwhile, ZIF–90–AAP/GO–EP exhibits excellent self-healing performance. The self-healing rate of ZIF–90–AAP/GO changes from negative to positive after 24 h, which results from the effective corrosion inhibition activity of ZIF–90–AAP for carbon steel based on the pH-triggered controlled release of AAP. The developed pH-responsive 2D/3D GO-based composite coating is very attractive for the corrosion protection of carbon steel.