Investigation of Dielectric Properties of Water Dispersion of Reduced Graphene Oxide/Water Nanofluid Composite

In nanofluid composites, competing interactions, interplay and proximity effects at the interface between the different constituents often lead to interesting physical properties, sometimes to novel effects and to new functionalities. In this paper, we focus our interest on the electrical and dielectric properties of the graphene oxide (GO)/water nanofluid composite and on their modeling. These properties are reported in the frequency range 1-1 MHz and in the temperature range from 295 to 309 K. The temperature dependence of the DC electrical conductivity shows a typical negative temperature coefficient in resistivity (NTCR) effect of this material. The mechanism responsible for the change in resistivity is probably predominantly tunneling, wherein the GO particles are not in physical contact and the electrons tunnel through the water gap between them. The DC electrical conductivity obeys an Arrhenius law below and above a critical temperature; that allows us to calculate both activation energies. Moreover, the dielectric response was analyzed using complex permittivity formalism. A relaxation phenomenon is induced in the nanofluid suggesting that the presence of the GO particles greatly affects the dielectric properties of the water due to the polarization phenomenon created by them. The Havriliak-Negami model was used to fit the experimental results.