Electrochemical characterization of graphene-type materials obtained by electrochemical exfoliation of graphite

The oxygenated functional groups of graphene oxide (GO) allow for its dispersion in water, biocompatibility and influence the heterogeneous electron transfer rate of redox processes. Therefore, it's important to determine the experimental conditions leading to GO materials with the desired electrochemical properties for a given application. Herein, few layers electrochemically exfoliated graphene oxide (EGO) flakes were prepared by electrochemical exfoliation of graphite in 0.1 M H2SO4 and the effect of the electric field (applied voltage divided by the distance between the electrodes) was investigated. Raman and XPS analysis evidence two different regimes during the synthesis: slow kinetics of exfoliation at low voltage vs high concentration of OH• radicals at high voltage. The EGO sheets were successfully assembled on a glassy carbon electrode through an aminophenyl-film linker and characterized by cyclic voltammetry in 1 mM [Fe(CN)6]3-/4- to determine electrochemical surface area (ESA) and standard rate constant of electron transfer (k0). The two parameters scale with each other and are sensitive to the type of EGO, confirming the suitability of the platform used in this work to characterize the EGO materials. The highest ESA (0.08 cm2) and the high k0 (0.13 cm−1) were measured with EGO materials obtained at 8–10 V and 6 cm.