Sonication-free dispersion of large-area graphene oxide sheets using internal pressure from release of intercalated carbon dioxide

Abstract A new concept to disperse graphene sheets without sonication, significant size reduction, and any further removal of intercalating materials, is demonstrated using ejection pressure of CO₂ gas captured by water molecules dissolved in the interlayer of graphene and the ice structure surrounding it. After graphene oxide (GO) layers are swelled with water molecules, CO₂ gas is dissolved in the swelled interlayer of GO. The CO₂ gas within the GO layers is well maintained by the transformation of excess water molecules outside of interlayer to solid ice at low temperature (around -30 °C). The resulting CO₂-incorporating GOs are well dispersed in various solvents by the ejection pressure of stored CO₂ without sonication, and without additional treatment for removal of the intercalating material as surrounding ices spontaneously melt. We show that the lateral length of these well-dispersed GO sheets is 10 times larger than that of GO sheets obtained by the conventional sonication method.