Enhancing the corrosion resistance of aluminum by graphene oxide and reduced graphene oxide films

This study is carried out with the goal of improving the corrosion resistance of aluminum in a saline solution through coating with graphene oxide (GO) and reduced GO (ERGO). The GO layer was applied on an aluminum substrate and then electrochemically reduced by cyclic voltammetry in 0.01 M K2HPO4 solution to form a reduced graphene oxide layer. The surface morphology, structure, and crystallinity of the coated materials were characterized using scanning electron microscope (SEM), x-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and Raman spectroscopy techniques. To study the electrochemical corrosion behavior of the coated aluminum substrate, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods were performed in 3.5 wt% NaCl solution. The results showed that both GO and ERGO films uniformly covered the surface of the aluminum substrates with layered structures. A noteworthy elimination of oxygen-containing functional groups (OFGs) occurred upon the electrochemical reduction of the film, yielding a highly-reduced ERGO layer on the substrate. Furthermore, the electrochemical reduction process significantly increased the thickness of the GO coating. The electrochemical test results exhibited that both GO, and ERGO layers improved the corrosion resistance of the bare aluminum substrate. However, electrochemical reduction of the GO layer had adverse effects on the corrosion barrier properties of the GO coating.