Chemical Synthesis of De–Doped Polyaniline for High Performance Aqueous Supercapacitive Material

Abstract

De–doped polyaniline were prepared by processing the doped polyaniline with three different aqueous alkali: NH4OH, NaOH and NaHCO3. Compared with the doped polyaniline, de–doped polyaniline shows better electrochemical capacitor performance, lower resistance and better stability in 0.5 M H2SO4 aqueous solution. Especially, de–doped polyaniline treated by NH3.H2O exhibits the specific capacitance of 839 F g−1 at a current density of 3 mA cm−2, which is about 2–fold higher than that of doped polyaniline. The behaviors of the capacitance of de–doped polyaniline can be deeply investigated and explained by the organic semiconductor band theory. De–doped polyaniline is expected to show satisfying performance due to the formation of impurity levels that can reduce the gap width of the forbidden band, and holes formed in the valence band generate the hole conduction during the re–doping of the de–doped polyaniline in acidic electrolyte, all of which can increase electron transport capacity. The study reveals that the electrochemical performances of polyaniline, particularly capacitance, can be improved by a simple de–doping process.