Electrochemical Measurement and Simulation of Sulfuric Acid-Doping Polyaniline on Graphite Carbon Paper.

The sulfuric acid-doping polyaniline (H-PANI-HSO4) are applied to conduct the electrochemical measurement and simulation calculation to investigate the capacitance, electronic structure and energy band properties. The H-PANI-HSO4 growing on graphite carbon paper (H-PANI-HSO4/GCP) is applied as an electroactive electrode to investigate electrochemical properties. The Faradaic capacitance of H-PANI-HSO4/GCP electrode is ascribed to the reversible redox reaction of bisulfate anion doping/dedoping protonated PANI (H-PANI). Cyclic voltammetry measurement at a scan rate of 5 mV s − 1 determines an equivalent mean response current of 0.64 A g − 1 and a capacitance of 128.35 F g − 1 . Galvanostatic charge–discharge measurement determines specific capacitance from 129.06 to 116.88 F g − 1 at current densities from 0.5 to 2.5 A g − 1 . Cyclic voltammetry-based capacitance at equivalent current density of 0.64 A g − 1 is in accordance with galvanostatic charge–discharge-based capacitance at the current density of 0.57 A g − 1 . Electrochemical impedance spectrum measurements indicate that H-PANI-HSO4/GCP exhibits lower charge-transfer resistance, much lower Warburg resistance, higher quasicapacitance than H-PANI-HSO4 to approaching ideal capacitor. Density functional theory calculations indicate that H-PANI-HSO4 has a higher density of states (10.6 electron/eV) and lower bandgap energy (0.481 eV) than H-PANI (5.24 electron/eV, 1.449 eV), indicating its enhanced electronic conductivity. The electronic bandgap energy is accordingly decreased from 0.263 eV for H-PANI-HSO4/GCP to 0 for H-PANI-HSO4/GCP. Electrochemical measurement and simulation calculation investigation proves that H-PANI-HSO4/GCP electrode with anion-doped and protonated state exhibits higher electronic conductivity and capacitance performance to act as superior electroactive material. The LiClO4-interacted oxygen-containing carbon paper is designed to act as electroactive supercapacitor electrode substrates for energy storage application, which involves the polarized electrostatic force-induced interfacial adsorption between LiClO4 and hydroxyl and epoxy groups of OCP substrate. [ABSTRACT FROM AUTHOR]