Electrochemical Reduction of Graphene Oxide on the Gold Surface: Localized Electrochemical Impedance and In Situ Polarization Modulation Infrared Reflection Absorption Spectroscopic Studies

Graphene oxide (GO) plays an important role in the development of graphene-based nanomaterials and nanocomposites for clean energy, environmental, sensing, and medical applications. In the present study, scanning electrochemical cell microscopy-local electrochemical impedance spectroscopy (SECCM-LEIS) and in situ polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) were employed to study the reduction of graphene oxide at the gold electrode surface as a function of the applied electrode potential. GO was stable on the gold surface when the electrode potential was higher than -0.4 V and partially reduced to rGO in the potential region between -0.4 and -0.8 V. It was completely reduced to rGO at the potential lower than -0.9 V. The SECCM-LEIS results showed that the conductivity and capacitance of rGO were much higher than those of GO. The PM-IRRAS spectra confirmed the existence of oxygen-containing functional groups in GO. The C=O bonds in GO were reduced to the C-OH and C-O-C bonds in rGO, and the C/O ratio of rGO was slightly increased. During the electrochemical reduction, the amount of the C=C bonds in the aromatic ring was increased, while the amount of the nonaromatic C=C bonds was decreased. The findings in the present study shed light on the mechanism of electrochemical reduction of GO and provide a facile approach for the formation of rGO on metal substrates with controllable oxygen functional groups.