Carbon fragments are ripped off from graphite oxide sheets during their thermal reduction

Since the discovery of graphene, many different exfoliation processes of graphite oxide have been reported. Thermal reduction is the most often used method for graphene synthesis. It is a general assumption that during the exfoliation process water vapor and carbon-monoxide and -dioxide are produced. In this paper it is shown that more complex products are formed during this process. Graphite oxides, prepared according to Hofmann, Hummers, Staudenmaier and Brodie methods, having different C/O ratios, were exposed to thermal shock. The resulting fragments detected using a time-of-flight spectrometer exhibit that the fragment fingerprints are very similar for all graphite oxides. Our finding challenges the general assumption that only basic gases are formed during thermal exfoliation of graphite oxide. The full understanding of the exfoliation mechanism and products is crucial for reproducible scalable synthesis of reduced graphenes on a large scale.