MOF‐5@Phen@Chitosan/EP Coating: A Smart Dual‐Functionality Self‐Reporting and Corrosion‐Inhibiting Coating for Identifying and Suppressing Early Steel Corrosion

Steel corrosion beneath protective coatings remains a major threat to infrastructure safety, creating a need for coating that provide early warning and active inhibition. In this study, a multifunctional self‐reporting and anti‐corrosion coating system (MPC) is fabricated using MOF‐5 loaded with 1,10‐phenanthroline (Phen) and encapsulated within chitosan shells, enabling pH‐responsive release. Physicochemical, spectroscopic, and electrochemical analyses confirm successful Phen loading (25.06–29.70 wt.%), controlled release behavior, and dual functions of visible self‐reporting and corrosion inhibition. CLSM and Raman measurements further verify the formation of Fe(Phen) 3 2+ at corrosion sites and the suppression of Fe ion. EIS shows that a 5 wt.% MPC coating achieves a 342% impedance increase compared with neat epoxy after 42 days in 3.5 wt.% NaCl solution. Salt‐spray and immersion tests further demonstrate real‐time visual corrosion indication and long‐term protection. This work presents an effective strategy for integrating colorimetric reporting and active inhibition in MOF‐based intelligent coatings for early‐stage corrosion detection and suppression.