High corrosion resistance Ni-reduced graphene oxide nanocomposite coating

Abstract

This paper presents a high corrosion resistance Ni-graphene composite coating fabricated by co-electrodeposition on Cu substrate. First, GO was synthesized by improved Hummers' method, and then different concentrations of GO aqueous solution were introduced to Ni Watt's bath. During electrodeposition, GO and Ni ions were reduced simultaneously to form composite coating. The phase structure and morphology were covered by X-ray diffraction and scanning electron microscopy analysis, respectively. Atomic force microscopy (AFM) was employed to identify the surface topography of the coatings. Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and electrochemical impedance spectroscopy (EIS) were used to study the synthesis of GO and its reduction during the plating process. Corrosion resistance of nanocomposite and that of pure Ni coating were compared by applying potentiodynamic polarization spectroscopy (PDS). The results showed that by increasing the amount of graphene oxide in solution, there has been a significant reduction in corrosion current density. As the EIS result showed, the high amount of GO reduction was obtained in GO concentration of 0.6 mg ml-1 and current density of 8 A dm-2. It is in a good agreement with data obtained from PDS. Analyses showed that the corrosion current density of corresponding coating was improved up to 0.2 μA cm-2, which means an improvement of about 100 times compared to pure Ni coating.