Corrosion protection of mild steel by graphene-based films

Abstract

We explore the ability of reduced graphene oxide (RGO) and titanium dioxide-decorated RGO (RGO-TiO2) films to protect mild steel from corrosion in 3.5% NaCl. Graphene oxide (GO), prepared using a Modified Hummers method, was reduced using sodium borohydride. TiO2 nanostructures were generated on RGO in a dispersion. The synthesized materials were characterized using UV-visible spectroscopy (UV–vis), Fourier Transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), Thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The obtained results confirm the exfoliation of graphite, reduction of graphene oxide, and formation of predominantly anatase phase of TiO2, grown as nanotubes. Corrosion behaviour of mild steel, with coatings of GO, RGO and RGO-TiO2, was studied using Tafel polarization studies and Electrochemical Impedance Spectroscopy (EIS). Tafel results showed that GO, RGO and RGO-TiO2 shifted the corrosion potential anodically, indicating that they prevent the anodic dissolution of iron. A six order-of-magnitude reduction in the corrosion current was observed with GO-film-coated mild steel coupons, with further reduction resulting in the use of RGO and RGO-TiO2 composite films. Impedance analysis showed that the films exhibited significantly enhanced charge transfer resistance for corrosion of mild steel by more than an order of magnitude compared to uncoated mild steel.