A new perception to the spectroscopic, dielectric and impedance behavior of graphene oxide

Abstract

The present study explores the synthesis of graphene oxide (GO) using Hummer’s method followed by a characterization that uses XRD, FTIR, Raman spectroscopy, UV, zeta potential, dielectric, and impedance study. The study of XRD, FTIR, UV, and Raman spectra revealed the presence of polar functional groups containing oxygen and structural deformity induced in GO. The nature of the surface charge, hydrodynamic diameter, and stability of graphite and GO in colloidal solution was ascertained from the zeta potentiometer. Raman spectra and zeta potential showed the presence of defects. The dielectric study of GO pellets with variation in frequency (1 Hz to 1 MHz) revealed the large dielectric constant of GO (∼105 at 26 °C and 1 Hz), which is comparable to conventional perovskite titanates dielectric materials. Both Lydanne–Sachs–Teller (LST) and Debye’s models of dielectric relaxation were taken into account while explaining the findings of giant dielectric constant in GO. Various mechanisms such as the presence of polar groups, Dirac fermions, and surface plasmon resonance have been discussed to explain the giant dielectric constant and its subsequent variation with frequency. The frequency dependence impedance and dielectric spectra were fitted using origin software to analyze poly dispersive nature and departure from Debye’s relaxation with an appraisal of static dielectric constant, static resistance, optical dielectric constant, optical resistance, mean relaxation time, and spreading factor. Nyquist plot was exploited to study the conductivity behavior of the GO by measuring grain capacitance, grain resistance, grain boundary capacitance, grain boundary resistance, and electrode resistance as well as capacitance. An equivalent electrical circuit was proposed for the measured data and it was correlated with the experimental findings. The findings suggest that synthesized GO pellets can be used for replacing perovskite materials and ferroelectric materials in high-performance electronic devices and energy storage devices such as supercapacitors.