Synthesis and systematic characterization of functionalized graphene sheets generated by thermal exfoliation at low temperature

We describe the low-temperature thermal exfoliation of graphite oxide to obtain functionalized graphene sheets (FGSs). Graphite oxide, which is highly oxidized graphite produced by a modified Brodie method, is further exfoliated by a simple heat treatment at 270-275 °C under ambient Ar. The FGSs that are generated have fewer defects and less oxygen content than in commercial graphene sheets (GSs) prepared at high temperatures (>900 °C). X-ray photoelectron spectroscopy demonstrates a clear π-plasmon peak in the FGSs of the type that is seen in precursor graphite, but not in commercial GSs. Thus, our FGSs exhibit high 2D crystallinity and minimal defects.