The characteristics of exfoliated graphite derived from three intercalation methods: gas
phase intercalation of iron (III) chloride, modified Hummers method and an electrochemical
technique, were compared.
Despite the absence of strong oxidisers the electrochemical method produced a material
which is very similar to that of the modified Hummers method in virtually every respect.
These both produced a graphite oxide based material whilst the gas phase method resulted
in a stage 1 intercalation compound. The different materials demonstrated very distinctive
The gas phase material exhibits 3% mass loss during expansion but has a large amount of
residual intercalant. The graphite oxide based methods result in mass loss of up to 25% in
the expansion zone. For all three samples the residual impurities lead to a reduction in
oxidative resistance. Once removed all samples exhibit nearly identical oxidation behaviour.
All three methods delivered graphite nanoplatelets with a very high aspect ratio through
considerable expansion. Surprisingly the gas phase method caused persistent residual
damage. All three methods yielded a product with varying levels of basal and edge damage,
but the purified Hummers material exhibited marginally more ‘ideal’ characteristics. The
simplest but still effective technique was found to be the electrochemical approach.