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Title Spectrophotometric and Electrochemical Characterization of Phosphoric Acid-Doped Polyaniline Thin Film on ITO as Supercapacitor Electrode
Posted by Bryan Montalban
Authors Bryan M. Montalban, Mylene M. Uy, and Reynaldo M. Vequizo
Publication date 2019
Conference 20th International Union of Materials Research Societies - International Conference in Asia
Abstract A highly pseudocapacitive phosphoric acid-doped polyaniline thin film (PA-dPTF) was successfully synthesized and grown on indium tin oxide (ITO) for supercapacitor electrode application. Electropolymerization and deposition of a pseudocapacitive PA-dPTF on ITO was achieved via a facile potentiodynamic technique in a three-electrode electrochemical cell using different anilinium hydrochloride (AnH+) and phosphoric acid (H3PO4) electrolyte concentrations, scanned from 0.2 V to 0.9 V (vs. Ag/AgCl). Spectrophotometric and Electrochemical characterization of the PA-dPTF electrode was investigated using Fourier-transform infrared (FTIR) spectroscopy, optical absorption spectroscopy (OAS), cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD). FTIR analysis of PA-dPTF showed a 47%-51% degree of oxidation indicating an emeraldine salt (ES) form of polyaniline. The observed pi to polaron and polaron to pi* transitions using OAS further confirmed that the thin film was an ES having a HOMO-LUMO gap of 2.36 eV - 2.49 eV an indicative of a semiconducting properties. The electrode material exhibited a high specific capacitance of 314.24±17.06 F/g at 0.03 mA/cm2. Repetitive GCD of PA-dPTF electrode for 200 cycles displayed 81% capacitance retention with 90% coulombic efficiency. The electrode afforded a power density of 4.9 kW/kg with an energy density of 50.54 Wh/kg at 0.3 mA/cm2. Finally, Ragone plot showed that the electrochemical performance of the fabricated PA-dPTF lies between the boundary of a supercapacitor and a battery.
Index terms / Keywords Electrodeposition, electropolymerization, potentiodynamic, reaction order, apparent rate constant.