TY - GEN A1 - Karačić, Dalibor A1 - Gutić, Sanjin J. A1 - Vasić, Borislav A1 - Mirsky, Vladimir M. A1 - Skorodumova, Natalia V. A1 - Mentus, Slavko V. A1 - Pašti, Igor A. T1 - Electrochemical reduction of thin graphene-oxide films in aqueous solutions – Restoration of conductivity T2 - Electrochimica Acta N2 - Graphene oxide finds applications in different fields of science, including energy conversion. Electrochemical reduction of graphene oxide (GO) significantly improves its conductivity. However, the kinetics of this process depends on the solvent, supporting electrolyte, pH, and numerous other factors. Most studies report the macroscopic views and ex-situ properties of reduced GO. To expand the knowledge about GO reduction, in this study, we used cyclic voltammetry (CV), simultaneous 2 points and 4 points resistance measurement (s24), conductive atomic force microscopy (AFM), and theoretical calculations. Using CV, we demonstrated that the choice of supporting electrolyte (KCl or LiCl) influences the potential range in which electrochemical GO reduction occurs. The activation energy of this process was estimated to be below 30 kJ mol‒1 in both electrolytes, being significantly lower than that required for thermal reduction of GO. Simultaneous in situ s24 resistance measurements suggest that GO films reach a highly conductive state at deep negative potentials, with an abrupt, irreversible switch from non-conductive to the conductive state. However, conductive AFM presents a more exact picture of this process: the reduction of GO films starts locally while the formed conductive islands grow during the reduction. This mechanism was confirmed by theoretical calculations indicating that the reduction starts on isolated oxygen-functional groups over the GO basal plane, while clustered OH groups are more difficult to reduce. The presented results can help in tailoring reduced GO for a particular electrochemical application by precisely controlling the reduction degree and percentage of the conductive area of the reduced GO films. KW - Electrochemical reduction of graphene oxide KW - Supporting electrolyte effect KW - Simultaneous 2-point 4-point resistance measurements KW - Conductive atomic force microscopy KW - Theoretical calculations Y1 - 2022 UR - https://www.sciencedirect.com/science/article/pii/S0013468622002183 U6 - https://doi.org/10.1016/j.electacta.2022.140046 SN - 1873-3859 SN - 0013-4686 VL - 410 ER -