Fabrication of MIL-88A sandwiched in graphene oxide nanocomposites using a green approach to induce active/barrier protective functioning in epoxy coatings

Abstract

The MIL-88A as a Fe+3/fumarate-based metal-organic framework (MOF) was used for the modification of graphene oxide (GO). This MOF was grown successfully on GO sheets to achieve active corrosion inhibition and to improve barrier effect against corrosive agents. The electronic density functional theory with dispersion correction functional (DFT-D) computations revealed the interactions between the GO sheets and the complexes. The electrochemical impedance spectroscopy (EIS) and polarization analysis revealed an increase in the total resistance (79%) and a reduction in corrosion current density (83%) after 5 h immersion in the saline solution containing optimally synthesized MIL-88A/GO hybrid nanoparticles. This anti-corrosion pigment released 3.6 ppm Fe+3 and 225 ppm total carbon according to inductively coupled plasma-optical emission spectrometry and total organic carbon experiments. The scratched epoxy coatings with 0.15% of this nanocomposite showed active inhibition in EIS and salt spray study. Higher wet/dry adhesion strength values were detected in the coating incorporating synthesized particles. Also, the cathodic delamination results indicated a 50% and 42% decrement in the disbonded area compare to neat epoxy and epoxy/GO coatings, respectively. Finally, the EIS measurement confirmed modified GO sheets' excellent barrier effect. The coating damage percentage was calculated by the broad frequency range analysis method. The results expressed that the epoxy and epoxy-GO had 100% and 79% damage index after 105 days, while the damage index for the MIL-88A/GO epoxy coating was 4%.