Transport and thermoelectric properties of polyaniline/reduced graphene oxide nanocomposites

Abstract

Polyanilines (PANI)/reduced graphene oxide (RGO) nanocomposites are chemically synthesized. Their structure and morphology are characterized by scanning and transmission electron microscopies, x-ray diffraction and Raman spectroscopy. In addition, the nanocomposites' electrical, thermal and thermoelectric (TE) transport characteristics are investigated as a function of RGO content. The power factor and figure of merit (ZT) of PANI/RGO hybrids are deduced from measurements of the electrical conductivity (σ), Seebeck coefficient (α) and thermal conductivity (κ). Experimental results reveal that the properties of PANI/RGO composites are inherently dependent on the volume fraction of RGO. It is observed that electrical percolation follows a 2D conduction process which takes place for samples having 0.099 vol% RGO content. Unlike electrical conductivity, the thermal conductivity of PANI/RGO increases only slightly with the RGO fraction and is successfully fitted using a modified MG-EMA model which provides an interfacial (PANI/RGO nanoplatelets) resistance (Rk) of 4.9 × 10(-10) m(2) K W(-1). This low Rk value is attributed to good interactions between the planar geometry of RGO platelets and PANI aromatic rings through π-π stackings as evidenced by Raman spectroscopy and x-ray studies. Compared to that of pure PANI, the TE performance of PANI/RGO composites exhibits a ZT enhancement of two orders of magnitude.