The present study was designed to deposit Cu-Pt bimetallic nanoparticles into an electrochemically reduced graphene oxide (ERGO) layer as an active material for counter electrode (CE) of a dye-sensitized solar cell (DSSC). At first, GO nanosheets were deposited on the surface of fluorine-doped tin oxide (FTO) electrode through an electrical field by an electrophoretic deposition method. Then, GO layer was converted to the ERGO by applying a negative potential vs. Ag|AgCl|KCl (saturated) to the electrode. Cu particles were electrochemically grown on the ERGO/FTO electrode surface by a chronoamperometric method from CuSO4 (1 mM) aqueous solution during 50 s. Then, Cu/ERG/FTO electrode was immersed into H2PtCl6 (2 mM) solution to reduce PtIV ions into Pt0 species through a galvanic replacement process. The prepared electrodes were characterized using field emission-scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR) and energy dispersive X-ray spectroscopy (EDS). The FE-SEM image showed that the ERGO surface was decorated with bimetallic Cu-Pt nanoparticles. Some properties of CE such as the ability for catalytic activity in reduction of triiodide to iodide (I3−/I−) and low charge transfer resistance were investigated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. The EIS studies on various electrodes using I3−/I− redox couple demonstrated that a lowest charge transfer resistance value was obtained for the Cu-Pt/ ERGO nanohybrid. Also, CV of the Cu-Pt/ERGO/FTO CE exhibited the highest current density and catalytic activity. The current density-voltage (J-V) test on the fabricated DSSCs showed the highest power conversion efficiency (PCE) of 4.30% for DSSC fabricated using Cu-Pt/ERGO/FTO CE.
