Molecular Dynamics Studies of Graphite Exfoliation Using Supercritical CO2Chapter
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Springer Science+Business Media Dordrecht 2014. Molecular dynamics simulations are used to investigate the microscopic mechanisms of graphite exfoliation using CO2 at supercritical conditions. Two approaches are used: simulations in the canonical ensemble are done by keeping the atoms in the graphite structure fixed but increasing the interlayer separations above their normal value. This procedure allows us to determine the interlayer separation at which the CO2 molecules may be able to intercalate graphite at near and supercritical pressures and temperatures, and to evaluate self-diffusion coefficients at those conditions. In the second approach, the isothermal-isobaric ensemble is utilized allowing graphite to relax, to observe how the exfoliation process may take place at the various pressures and temperatures near and above the CO2 critical point. Analyses of the simulation trajectories reveal that the exfoliation process takes place at increasing rates as the pressure increases at constant temperature, with intercalation of CO2 molecules causing bending and then separation of graphene layers.
