Capacitive behavior and material characteristics of congo red doped poly (3,4-ethylene dioxythiophene)

Congo red doped poly(3,4-ethylene dioxythiophene) with loose granular morphology and some clear channels was synthesized by chemical oxidative polymerization using congo red as dopant and surfactant, and the formation mechanism of its morphology was confirmed by means of fourier transform infrared spectrum, X-ray diffraction, UV–Vis absorption spectrum and scanning electron microscope. The influences of feeding molar ratio of congo red to ethylene dioxythiophene on its electrochemical properties were discussed by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The results showed that the maximum specific capacitance of congo red doped poly(3,4-ethylene dioxythiophene) could reach 206 F/g when the feeding molar ratio of congo red to ethylene dioxythiophene was 0.08:1, which was 58% higher than that of poly(3,4-ethylene dioxythiophene). The improved specific capacitance of congo red doped poly(3,4-ethylene dioxythiophene) could be due to its special molecular structure and loose granular morphology with some clear channels.