Mass production of graphene oxide from expanded graphite

In a deviation from the conventional Hummers method, a spontaneous expansion approach was introduced with expanded graphite as the precursors. The intercalating agent (H2SO4) was able to penetrate into the expanded graphite; this had further expanded the graphite and as a result, a foam-like intermediate was produced. The foam-like graphite was more easily oxidized in reaction with the oxidant (KMnO4) to form graphene oxide (GO). Fully exfoliated GO was obtained with expanded graphite having the median diameter similar to 15 mu m as the precursors. This procedure was much safer and productive in scalable applications than the conventional Hummers methods. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.