Effect of reduced graphene oxide on the enhancement of thermoelectric power factor of γ-NaxCo2O4

The gamma-NaxCo(2)O(4)/reduced graphene oxide (rGO) with various rGO contents (x = 0, 0.02, 0.04, 0.06, and 0.08 wt %) were synthesized by the polymerized complex method and sintered by solid state reaction. Temperature dependence of electrical resistivity, the Seebeck coefficient and power factor was investigated in the range of 312-859 K. The lower electrical resistivity of 80 mu Omega m was achieved for 0.02 wt%rGO, while high Seebeck coefficient of 155 mu V K-1 for 0.08 wt%rGO at 859 K. Maximum power factor of 281 mu W m(-1) K-2 at 859 K was obtained at rGO content of 0.02 wt% and higher than gamma-NaxCo(2)O(4) (98 mu W m(-1) K-2). Results suggested that rGO incorporation in the gamma-NaxCo2O4 significantly enhanced power factor of thermoelectric materials.