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

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.