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Chemistry will play an increasingly important role in the realization of graphene applications. The chemical formation of covalent carbon–carbon bonds involving the basal plane carbon atoms offers an alternative approach to the control of the electronic properties of graphene, and potentially allows the generation of insulating and semiconducting regions in graphene wafers. This review summarizes recent progress in the covalent modification of epitaxial graphene and the effect that chemistry has on the electronic and magnetic properties of the material.

We present the results of THz, infrared and magneto-optical measurements performed on graphite nanoplatelet films as a function of temper- ature (4.2-300K) and magnetic field (0-17.5T). An effective medium analysis of the low-energy spectral response indicates that the nanoplatelet material is well described by a Drude function plus two infrared absorption bands. Interestingly, the Drude plasma frequency ( 1675cm 1 ) decreases slowly with temperature, whereas the carrier scattering rate ( 175cm 1 ) is temperature independent. Furthermore, measurements in an applied magnetic field at 4.2K show that a large portion of the Drude spectral weight is transferred to finite frequency features corresponding to various Landau-level transitions. Some of these transition energies scale as p B, as expected for Dirac-like quasi-particles in graphene and observed in other graphene-like materials. Thus, our results are consistent with recent theoretical calculations indicating that the spectrum of multilayer graphene can be decomposed into subsystems effectively identical to monolayer or bilayer graphene.

We report the thermal conductivities of graphite nanoplatelet-epoxy composites prepared by exfoliation of natural graphite flakes of varying lateral sizes. We found that utilization of natural graphite flakes of the optimum lateral dimensions (∼200-400 µm) as a starting material for exfoliation significantly enhanced the thermal conductivity of the composite. In order to understand this enhancement we developed a procedure for evaluation of the particle size distribution of graphite nanoplatelets and correlated the measured distributions with the resulting thermal conductivities. In order to expand the scope of our study we applied our statistical and thermal analysis to commercially available graphite nanoplatelet materials.