Controlled oxidation level of reduced graphene oxides and its effect on thermoelectric properties

We investigated the thermoelectric properties of reduced graphene oxide (rGO) as a function of the oxidation level of rGO. rGO among graphene derivatives was selected as a thermoelectric material since rGO bucky paper shows low thermal conductivity due to the phonon scattering at the junctions of rGO nanoplatelets. The oxdation level of rGO was controlled by differing the amount of chemical reductant (hydrazine) used to reduce graphene oxide (GO) to rGO, which correspondingly affected the electrical conductivity and Seebeck coefficient of rGO film. In this study, the maximum of figure of merit (ZT) was found to reach to 1.1x10(-4) at 298 K for rGO reduced with the hydrazine of 1000 mu L. These results provide the first experimental evidence that the thermoelectric performance of graphene and its derivative can be controlled by the oxidation level of graphitic nanoplatelets.