Energetically efficient and electrochemically tuneable exfoliation of graphite: process monitoring and product characterization

In this work, graphene oxide was prepared by electrochemical exfoliation of graphite in sodium dodecyl sulphate and sodium dodecylbenzene sulphonate aqueous solution. Two different working electrodes were investigated: an electrode prepared from natural graphite flakes and a commercial natural graphite rod. The working electrode was polarized in a two-electrode system by using platinum counter electrode and by a multistep change of polarity or by single anodic and cathodic polarization. The voltage value ranged from 2.5 to 3.2 V. By monitoring the current transients and the colour of the resultant solutions, it was shown that the exfoliation process depends on the type of working electrode, surfactants and applied voltage value. The multistep change of polarity was more effective compared to single polarization. The ultraviolet–visible spectrophotometry and Raman spectroscopy indicated the presence of defects within the graphene structure, while FTIR spectroscopy indicated the presence of oxygen functional groups, which is characteristic of graphene oxide (GO). Dynamic light scattering revealed that the solutions obtained in this work contained GO sheets within the size of 10–600 nm. Atomic force microscopy measurements proved that the obtained product contains multilayer sheets. The energy consumption for the process carried out in this work ranges from 0.084–0.038 kWh g−1, and therefore this process is considered to be a low-energy and cost-effective process.