Tannic acid-copper metal-organic frameworks decorated graphene oxide for reinforcement of the corrosion protection of waterborne epoxy coatings

Waterborne anticorrosion coatings have aroused tremendous attention in the metal protection field due to their environmentally friendly properties. However, the limited barrier performance and poor resistance to corrosive species severely impede its practical applications. Herein, tannic acid-copper metal-organic framework (TA-Cu) was first synthesized via oxidative coordination and then assembled with graphene oxide to obtain TA-Cu-decorated graphene oxide (TAG), which was utilized to improve the anticorrosion performance of waterborne epoxy (WEP) coatings. Electrochemical measurements demonstrated that the impermeability of WEP has been significantly enhanced with the incorporation of TAG. Meanwhile, local electrochemical impedance spectroscopy tests indicated that the corrosion reaction at defected region can be effectively suppressed, presenting an active anticorrosion function. The protection mechanisms are attributed to (1) TA-Cu contributed to the dispersion of graphene oxide in WEP and impeded the intrusion of aggressive ions and (2) the coordination and adsorption of TA on steel inhibited the redox process and corrosion extension.