Anthraquinone-2-sulfonic acid-loaded polyaniline nanostructures: Construction of symmetric supercapacitor electrodes thereof

Polyaniline (PANI) nanostructures were synthesized via an acid-free green route using redox-active, water-soluble 9,10-Anthraquinone-2-sulfonic acid sodium salt (AQSA). As a counter anion for the PANI backbone, the AQSA plays an important role in polyaniline (PANI) chain growth and as a morphology regulator. The AQSA doped PANI shows pronounced specific capacitance with effective cycling stability. As-synthesized nanotubular structures of PANI_AQSA (0.5, 1.0, and 1.5) with various concentration ratios of aniline to AQSA were achieved in appreciable yield. The intrinsic physico-chemical properties were analyzed using various physico-analytical techniques such as Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive Spectroscopy (EDS), powder X-ray diffraction analysis (XRD), Fourier Transmission Infrared spectroscopy (FT-IR), X-ray Photo Electron Spectroscopy (XPS), and Raman analysis. Nanotubular structures of PANI_AQSA were analyzed using FESEM studies. The electrochemical studies, galvanostatic charge-discharge (GCD), and Electrochemical impedance spectroscopy (EIS) were methodically investigated. PANI_AQSA_1.5 portrays enhanced specific capacitance of 440 Fg−1at 1 Ag−1(three-electrode system) in 1 M sulphuric acid electrolyte than its regular Cl−counter ion (276 Fg−1at 1 Ag−1). The fabricated symmetric PANI_AQSA//PVA_H2SO4//PANI_AQSA supercapacitor showed a specific capacitance of 391 Fg−1at 1 Ag−1with 93 % capacitance retention for ~1000 cycles.