Study on electrochemical performance of porous integrated PANI-Fe in supercapacitors

The iron-coordinated polyaniline (PANI-Fe) integrated nanomaterials was prepared by chemical oxidative and in-situ electrochemical polymerization, which was applied to supercapacitor electrodes. The N–Fe coordination bond is formed between FeCl3 and the N of quinone diimine to enhance the interaction of the polyaniline molecular chain. The PANI-Fe electrode material forms a crosslinked porous fiber framework through two-step oxidation, which greatly improves the energy storage capacity of PANI-Fe. PANI-Fe achieves higher capacitance of 642 F g−1 at 1 A g−1 than PANI of 310 F g−1, and maintains high capacitance retention of 82.4 % when the current density increases from 1 to 10 A g−1. According to first-principles calculations, the Fermi energy (N(E)) of PANI-Fe drop down to 0.265 eV from 0.901 eV of PANI, which proves that its conductivity is improved. The change of the electrostatic potential of PANI-Fe indicates that the formation of the N–Fe coordination bond can improve the carrier transport behavior. PANI-Fe has a smaller HOMO-LUMO energy gap than PANI, indicating that the formation of N–Fe coordination bonds can increase the electrical activity of PANI.