Study on the specific capacitance of an activated carbon cloth modified with reduced graphene oxide and polyaniline by cyclic voltammetry

Abstract

This work describes a two-step process for the electrochemical coating of reduced graphene oxide (RGO) and polyaniline (PANI) onto an activated carbon cloth (ACC) by cyclic voltammetry (CV). The fact that the two syntheses are carried out independently of each other, makes it possible to select the experimental conditions for each one and to study the electrochemical response of RGO, PANI, and PANI onto RGO (RGOPANI), separately. Thus, by modifying the potential limits of the aniline-polymerization reaction, it was possible to observe the influence of RGO and the maximum amount of PANI that the carbon cloth can receive in terms of proper electrochemical response. Electrochemical properties were characterized by CV, galvanostatic charge-discharge curves (using three or two-electrodes symmetric cell configurations) and electrochemical impedance spectroscopy (EIS). A maximum improvement of 25%, 56% and 61% over the initial specific capacitance of ACC (about 129 F g−1) were obtained for RGO, PANI and RGOPANI coatings, respectively. Good cycling stability retaining 83% of the initial capacitance, after 1000 cycles stability test, was obtained for RGOPANI sample. Promising results of energy and power densities were also achieved. In the analyses by Fourier transform infrared spectroscopy (FTIR), the PANI-bands could be clearly identified which is indicative of a significant presence of PANI. Field emission scanning electron microscopy (FESEM) showed the morphology of RGO, PANI and RGOPANI onto the ACC fibers. These analyses helped to explain the electrochemical results.