An impedance spectroscopy study of the rotation and reorientation of water molecules in hydrated graphite oxide

Graphite oxide (GO) has been prepared by the modified Hummers method and hydrated to different concentrations. Samples were then characterized by nuclear magnetic resonance spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction analysis, and gas adsorption. The results confirmed the existence of water molecules at two types of sites, namely the two-dimensional space between GO layers as well as inter-grain voids. Detailed impedance spectroscopic measurements have been performed to study the rotation and reorientation dynamics of confined water. Two dielectric loss peaks were observed in hydrated GO and attributed to relaxational motions of water molecules. The peak at the higher temperature arises from the rotation of intercalated molecules along the axis of their hydrogen bonds to hydroxyl radicals on the graphite oxide layers. The peak at lower temperature corresponds to the relaxation of inter-grain species, a relaxation that seems to deviate from Arrhenius behavior at higher temperatures. (C) 2013 Elsevier Ltd. All rights reserved.