Synthesis, characterization and supercapacitors of electrically conductive PPy/graphene/rare earth ions composites

PPy/graphene/rare earth ions (PPy/GR/RE3+) were prepared using an in situ chemical polymerization of the monomer in the presence of FeCl3 oxidant and p-toluenesulfonic acid dopant. The PPy/GR/RE3+ composites were characterized by FT-IR spectroscopy, four-point probe conductivity, scanning electron microscopy and transmission electron microscopy. The maximum conductivity of PPy/GR/Gd3+ composites is about 9.71 S/cm found with 1 wt% GR and 2 wt% Gd3+ at room temperature. The capacitance of the composite electrodes was investigated with cyclic voltammetry. As results of this study, the PPy/GR/Gd3+ was effective to obtain fully reversible and very fast faradaic reaction. Hence, the PPy/GR/Gd3+ could contribute to the pseudo-capacitive charge storage. The PPy/GR/Gd3+ exhibited higher specific capacitance of ~238 F/g at 1 A/g current density. Thermal gravimetric analysis demonstrates an improved thermal stability of PPy in the PPy/GR/Gd3+ composites.