Effects of polydopamine functionalized graphitic carbon nitride‑cerium oxide nanofiller on the corrosion resistance of epoxy coating

It's of great convenience and economy to incorporate novel functionalized nanofillers with superior anticorrosive properties to further elevate the corrosion protective period of epoxy coating. For this purpose, we fabricated finely dispersed cerium oxide grafting polydopamine modified graphitic carbon nitride (g-C3N4@PDA@CeO2) via self-polymerization method and hydrothermal technique to promote the epoxy coating's anticorrosion performance on P110 substrate. The XRD, XPS, TGA, and SEM analyses were employed to qualitatively verify the successful synthesis of g-C3N4@PDA@CeO2 nanocomposite. The results obtained from EIS experiments showed that the g-C3N4@PDA@CeO2 epoxy coating possessed superior corrosion resistance, which maintained a modulus value (|Z|0.01Hz) of 4.737 × 107 Ω cm2 after the entire soaking process. Conversely, pure epoxy coating presented the |Z|0.01Hz which became two orders of magnitude lower. Additionally, a prominent decline in the corrosion current value (Icorr = 5.122 × 10−11 A/cm2) was observed from the potentiodynamic polarization curve of g-C3N4@PDA@CeO2 epoxy coating, decreased 3 orders of magnitude better than neat epoxy (Icorr = 4.421 × 10−8 A/cm2). The enhancement mechanism on the epoxy coating's anticorrosion property could be explained by synergistic effects of PDA's modification and the grafting of CeO2 that endowed the epoxy coating with better barrier effect to electrolytes and great corrosion inhibition property, which conjointly extended corrosion protection period.