Corrosion study of electrophoretically deposited graphene oxide coatings on copper metal

Abstract

This work aims to develop novel corrosion resistant coatings for copper metal. Graphite oxide was produced from graphite powder by improved Hummers' method. Graphene oxide (GO) was obtained by sonicating the suspension of graphite oxide and water. The thickness of GO sheets was found in the range 1–2nm as determined by atomic force microscope (AFM). Graphene oxide (GO) coatings were deposited on copper strips via electrophoretic deposition (EPD) from GO/water suspension by making copper strips as anode. The EPD parameters such as voltage and suspension concentration were optimized to obtain uniform GO coatings. The GO coatings obtained at a potential of 5V and deposition time of 10s (optimized parameters) were found to have a thickness of ca. 400nm as determined by AFM. GO coatings were partially reduced during the EPD process due to the removal of oxygen containing functional groups as revealed by Fourier transform infrared spectroscopy. Corrosion resistance of GO-coated samples was studied in 3.5% NaCl solution by Tafel analysis and electrochemical impedance spectroscopy. The corrosion potentials of GO-coated copper samples shifted to more noble potentials and corrosion rates of coated samples were found to be 6× lower than bare copper suggesting that GO coatings are promising coatings against aqueous corrosion of copper.