Paramagnetic Impurities in Graphene Oxide

We report on electron paramagnetic resonance and nuclear magnetic resonance study of graphene oxide produced by the Hummers method. We show that this compound reveals isolated Mn2+ ions, which originate from potassium permanganate used in the process of the sample preparation. These ions are likely anchored to the graphene oxide planes and contribute to the H-1 and C-13 spin-lattice relaxation.