The influence of copper addition on the electrical conductivity and charge transfer resistance of reduced graphene oxide (rGO)

Abstract

The electrical conductivity and charge transfer resistance (R_ct) of reduced graphene oxide (rGO) with the addition of copper are reported. The samples of rGO with copper addition were successfully synthesized via in situ chemical exfoliation using a microwave-assisted technique. Annealing was performed at various temperatures to determine the optimal annealing temperature for the sample with the best electrical conductivity performance. The resulting samples were characterized using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) characterization, X-ray diffraction (XRD), Raman spectrometry, energy dispersive X-ray (EDX) spectrometry, scanning electron microscopy (SEM), four-point probe, and electrochemical impedance spectroscopy (EIS). The highest conductivity value of 24.85 S cm⁻¹ was obtained for the rGO sample with addition of 1 wt% copper and annealing treatment at 300 °C for 45 minutes. The electrochemical properties of the samples were characterized using electrochemical impedance spectroscopy (EIS), resulting in a charge transfer resistance (R_ct) value of 3.86 Ω for sample B with the addition of 1 wt% copper. A possible reaction mechanism and explanations for the influence of Cu, Cu₂O, and CuO on the electrical conductivity and charge transfer resistance value of rGO are also described in this report.