Kinetic study of graphene oxide synthesis by electrochemical exfoliation of graphite

Abstract

A kinetic study of graphene oxide (GO) synthesis using electrochemical exfoliation of graphite in the acidic and alkaline electrolyte has been carried out. The effects of temperature (301–333 K), sulfuric acid concentration (0.3–0.6 M), pH (0.3–11.2), current density (12–40 mA/cm2), and graphite density (1.72–1.92 g/cc) on the rate of GO formation have been examined. The GO exfoliation rate was found to be unaffected by graphite density; therefore, all the kinetic was studied with the graphite density of 1.82 g/cc. The GO exfoliation rate increased with a sulfuric acid concentration in the electrolyte. The temperature was seen to enhance the rate of GO synthesis. The activation energy of GO exfoliation was found to be 33.53 kJ/mol in a temperature range of 301–333 K. Based on the findings the mechanism was proposed and the rate law was deduced.. The surface reaction of anions during intercalation and de-intercalation in the interstices of graphite has been found to be the rate-controlling step. Synthesized GO was characterized with transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The kinetic model has been developed to fit the GO exfoliation rate within a pH range of 0.3–1.1.