Electrochemical performance of graphene oxide/epoxy/iron composite coatings for corrosion protection of X52 mild steel in NaCl solution

Abstract

In this study, graphene oxide/epoxy coatings with varying iron particles contents were developed. The anticorrosive properties of the graphene oxide/epoxy/iron (GO/EP/Fe) coatings were investigated in a 0.5 M NaCl solution using electrochemical techniques such as chronopotentiometry, potentiodynamic polarization, and Electrochemical Impedance Spectroscopy (EIS). The results showed that the addition of 0.5g of iron to the coating significantly improved its corrosion inhibition performance. Furthermore, scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) and optical microscopy (OM) observations revealed that the iron particles near the substrate/coating interface corroded first, providing both cathodic and anodic protection for the steel through the electrical connection with graphene oxide. DFT research demonstrated that graphene oxide interact with metallic surface through active sites on molecule, which are recognized by HOMO-LUMO distributions. The simulations (both Monte Carlo and molecular dynamics) show that graphene oxide adsorbs spontaneously and approaches the steel surface gradually, forming a high-density electronic cloud on the metal surface. Additionally, the Monte Carlo simulations support the experimental results showing that an increase in iron content led to a decrease in adsorption energy.