PH-Sensitive Self-Healing Waterborne Epoxy Coating: Polydopamine Grafted Graphene Oxide with 2-Mercaptobenzimidazole Inhibitors and Cerium Cation Towards Anti-Corrosion Performance

The development of smart coatings with active protection is a promising approach to prolonging the service life in extreme environments. Herein, the corrosion inhibitors 2-mercaptobenzimidazole (MBI) and CeO2 were in situ loaded onto the surface of graphene oxide (GO) by dopamine (DA) polymerization, and we ultimately obtained the multifunctional composite MBI@CeO2@PDA@GO (MCPG). The electrochemical impedance spectroscopy (EIS) results revealed that after 30 days of immersion in the corrosive media, the |Z|0.01 Hz value of MCPG/WEP coating remained at 3.7 × 109 Ω/cm2, which displayed four orders of magnitude higher than that of pure WEP coating (1.4 × 105 Ω/cm2). In a 200 h salt spray test, the MCPG/WEP coating also demonstrated minimal corrosion products and bubbles, affirming the exceptional corrosion-inhibiting effect and excellent self-healing performance. Consequently, the synergistic combination of pH-sensitive properties and outstanding barrier effect imparted dual active/passive anti-corrosion capabilities to the coating, resulting in long-lasting metal protection.