In this report we show that the photochemical oxidation of monolayer graphene is strongly dependent on its underlying substrate. It was found that chemical vapor deposition-grown monolayer graphene transferred onto a silicon wafer is more easily oxidized compared to graphene that was left on the copper substrate or transferred onto a H2-annealed copper foil. The differences in the degree of oxidation were tentatively attributed to the varying energies of adhesion between the graphene and the underlying substrate. Our result has significant implications for the outdoor use of graphene as a transparent conducting material.
