A simple method to examine room-temperature corrosion of graphene-coated copper foil after stored for 2.5 years

Abstract

We report the method for measuring the oxidation level of graphene-coated copper and uncoated copper upon exposure to an ambient condition (relative humidity, RH ∼ 80%) for 2.5 years using the combination of UV–vis reflectance spectroscopy and the optical simulation. In the simulation, we consider the oxide layer as an effective medium which contains a certain fraction of two stable oxide phases of copper, namely Cu2O and CuO (which is widely known as the indicator of the severe oxidation process). The results show that the graphene-coated copper and uncoated copper have been oxidized with the similar oxide thickness around 15 nm. However, the percentage of Cu2O and CuO in graphene-coated copper, which is 64% and 36%, respectively, differs from that of uncoated copper, which is 30% and 70%, respectively. The amount of CuO in the graphene-coated copper turns out smaller than that on uncoated copper, which means that graphene may slow down the oxidation process but not completely prevent the oxidation of the underlying copper. The energy dispersive x-ray spectroscopy (EDS) confirms that there is more oxygen on the uncoated copper. These findings could open new possibilities for nondestructive characterizations and studies of graphene-coated metals with potential corrosion.