Ultrasonicated-ozone modification of exfoliated graphite for stable aqueous graphitic nanoplatelet dispersions

A novel ultrasonicated-ozonolysis (USO) processing method has been applied to commercially available exfoliated graphite (EG) with the aim of producing stable aqueous graphitic nanoplatelet (GNP) dispersions that are suitable for ink-jet printing and electrophoretic deposition. The processing has been compared to other low energy and environmentally friendly electrochemical exfoliation (EE) techniques. The results show USO can be used to prepare highly stable aqueous dispersions from both low and high surface area EG. The level of oxygen functionalization can be easily controlled with processing time as can the dispersion concentration. The degree of disorder in the GNP structure is similar to existing EE methods but offers higher yields without the need to remove any chemicals post-processing. Ink-jet printing onto heated quartz substrates produced films which reached electrical conductivities of 1400 s m(-1) after annealing. The films printed from USO-processed EGs had higher conductivity and significantly reduced thickness as compared to films printed from aqueous dispersions of reduced graphene oxide.