Effect of doping ions on capacitance properties of polypyrrole/ functionalized single-walled carbon nanotubes composites

Polypyrrole/functionalized single-walled carbon nanotubes composites (PPy/F-SWNTs) were electrochemically prepared in dispersive solution of pyrrole (Py) and F-SWNTs with or without doping ions. The effect of in-situ doping ions including Cl^-, CIO₄^-, toluenesulfonate (TOS^-) and dodecylbenzenesulfonate (DBS^-) on the capacitance performance of the composites was investigated by cyclic voltammetry (CV), galvanostatical charge/discharge and electrochemical impedance spectroscopy (EIS) techniques. Except the pristine composite and the composite doped by DBS^-, the others exhibited notable electrochemical capacitance behaviors. Furthermore, the specific capacitance of PPy-Cl/F-SWNTs (polymerization charge was 2 mAhcm^-2) reached 241 Fg^-1 at the scanning rate of 10 mVs^-1. PPy-TOS/F-SWNTs (polymerization charge 2 mAhcm^-2) had greater capacitance and charge/discharge rate than the former did. Even at the scanning rate of 200 rnVs^-1, its specific capacitance was still up to 172 Fg^-1. But with heaver doping ion (TOS^-), PPy-TOS/F-SWNTs (polymerization charge 2 mAhcm^-2) had a slightly smaller specific capacitance, such as 196 Fg^-1 at the scanning rate of 10 mVs^-1.