Tuning F-doped degree of rGO: restraining corrosion-promotion activity of EP/rGO nanocomposite coating

Abstract Given that graphene features high electrical conductivity, it is a kind of material with corrosion-promotion activity. This study aimed to inhibit the corrosion-promotion activity of graphene in coatings. Here, we report an exciting application of epoxy matrix (EP)/F-doped reduced graphene oxide (rGO) coatings for the long-term corrosion protection of steel. The synthesized F-doped rGO (FG) did not reduce the utilization of rGO by a wide margin and possessed distinctive electrically insulating nature. The electrical conductivity of rGO was approximately 1500 S/m, whereas those of FG-1, FG-2 and FG-3 were 1.17, 5.217 × 10-2 and 3.643 × 10-11 S/m, respectively. FG and rGO were then dispersed into epoxy coatings. The chemical structures of rGO and FG were investigated by transmission electron microscopy (TEM), scanning probe microscopy (SPM), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). EP/FG coatings exhibited outstanding corrosion protection in comparison with blank EP and EP/rGO coatings mainly because the corrosion-promotion effect of rGO was eliminated. The anticorrosion ability of EP/FG coatings was improved with increased F-doped degree of FG. In addition, electrochemical impendance spectroscopy (EIS) results indicated that the Rc values of EP/FG-2 and EP/FG-3 were four orders of magnitude higher than those of EP/rGO in diluent NaCl solution (3.5 wt.%) after immersion for 90 days.