Suppression of copper surface oxidation by electrophoretically deposited graphene oxide film

This work investigated the oxidation suppression effect of a reduced graphene oxide (rGO) film applied to a Cu substrate, which may have application in electrical connectors. To ensure prolonged low electrical contact resistance, a thin GO film was formed using an electrophoretic deposition method and subsequently heated to generate rGO. The surface morphology and thickness of the rGO film were assessed using atomic force microscopy and transmission electron microscopy. The thickness of the rGO film was estimated to be 5–7 nm, and the electrical contact resistance for the Cu substrate with and without an rGO film was 20 and 8 mΩ, respectively, at a contact load of 2 N. After accelerating the oxidation of the substrate by heating for 30 min at 180 °C under a dry air atmosphere, the formation of a Cu2O layer on the Cu substrate was confirmed by Raman spectroscopy and electron energy loss spectroscopy. The thickness of this oxide layer with and without an rGO film was 1.5 and 6 nm, respectively. In addition, the electrical contact resistance for the Cu substrate with and without the rGO film was 40 and 200 mΩ, respectively, at a contact load of 2 N. These results suggest that the thin rGO coating suppressed oxidation of the metal substrate while also suppressing the increase in contact resistance.