In situ electrochemical exfoliation of embedded graphite to superficial graphene sheets for electroanalytical purposes

Abstract In this study we propose an in situ low-cost electrochemical treatment by cyclic voltammetry (CV) for graphene oxide (GO) synthesis on the surface of graphite/ABS composite electrodes. Higher efficiencies were achieved while CV treatments were carried out in alkaline (KOH) background electrolyte, applying an elevated number of successive cycles (1000) under high scan rate (2000 mV s−1), being the oxidation potential observed at +1.5 V. After treatment, scanning electron microscopy and atomic force microscopy images pointed to an increase on both surface area and roughness; the results for Raman spectroscopy and FT-IR complemented the elucidation, demonstrating structural changes to the electrode after treatment, and confirming the formation of GO. Moreover, a relevant decrease in charge transfer resistance was observed by EIS (Rct, 50 Ω) and a higher heterogeneous electron transfer rate constant (k0, 1.50 × 10−4 cm s−1) were verified after surface electrode treatment, indicating the faster transfer of electrons to redox probes on this surface. Such a surface treatment was thus effective and reproducible (RSD = 5.5%; n = 10) allowing an easy surface renewal just by smooth polishing. Treated electrodes were applied to dopamine (DP) quantification, showing stable amperometric responses, higher peak current intensities (3-fold) and improved detectability of DP when compared to modified electrodes obtained by drop casting (CRGO or ERGO modifications), which indicates that the proposed treatment is simpler and more appropriate. Wide linear range, higher sensitivity and precision were observed in the analytical method developed for DP via BIA-AMP and SWV.