Several authors [11, 13, 14, 18] have

performed voltammetric cycling of exfoliated GO sheets from colloidal suspensions and found that electrochemical reduction for different functional groups in GO are dependent on the reduction potential. In this work, voltammetric cycling was used to electrochemically reduce GO films to ERGO in KOH solution. Methods Chemicals All chemicals such as KOH, KCl, K4[Fe(CN)6], and K3[Fe(CN)6] were of Analar grade and procured from Sigma Aldrich (St. Louis, BI 2536 solubility dmso MO, USA). Synthesis of GO GO was synthesized using a modified Hummers’ method [19]. GO was dispersed in a beaker filled with distilled water and sonicated for 5 h. GO dispersion with a concentration CB-839 research buy of 0.3 mg cm-3 was poured on a graphite sheet in the jar and evaporated overnight in an oven at 60°C. Material characterization Field emission scanning electron microscopy (FESEM) using a Quanta 200F instrument (FEI, Hillsboro, OR, USA), was used to capture the images of the evaporated GO and ERGO layers on the graphite sheet. Fourier transformed infrared (FTIR) spectroscopy was carried out using Spectrum 400 instrument while Raman spectroscopy was done with a Renishaw inVia Raman microscope (Wotton-under-Edge, UK) using (λ =

514 nm) laser GDC-0973 nmr excitation. Electrochemical methods Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were done using a potentiostat / galvanostat, Autolab PGSTAT-302N from Ecochemie (Utrecht, the Netherlands). A general purpose electrochemical software installed in the computer interfaced with a USB card (USB_IF030) was used to run the CV experiments while frequency response analysis (FRA) software

was used to run the EIS experiments. The CV and EIS experiments were done in a single compartment cell. A mercury oxide (Hg/HgO) reference electrode (RE) and graphite rod counter electrode (CE) was used in the voltammetric cycling for the reduction of GO films in 6 M KOH solution at a scan rate of 50 mV·s-1. The CV experiments performed in 6 M KOH solution and [FeII(CN)6]3-/4- redox couple in 0.1 M KCl supporting electrolyte were done on stationary electrodes. A two-electrode configuration was used in the EIS experiments using the working electrodes (WE), and a saturated very calomel electrode (SCE) as the reference and counter electrode (RE-CE). The EIS measurements were performed over a frequency range of 100 kHz to 10 mHz, with an acquisition of 10 points per decade, and with a signal amplitude of 5 mV around the open circuit potential. Analysis of the impedance spectra was done by fitting the experimental results to equivalent circuits using the nonlinear least-square fitting procedure with the chi-squared value minimized to 10-4. All experiments were performed at room temperature 300 K.