Analysis of the electrochemical behavior of PANI synthesized galvanostatic method through electrochemical impedance spectroscopy

Researchers across various fields have become interested in intrinsically conductive polymers (ICPs) due to their stability, ease of use, and conductivity. Polyaniline (PANI) is a prime example, with applications ranging from corrosion protection, electrochromic devices, and energy storage (electrodes). Despite its versatility, few studies explore its electrochemical behavior using the technique of electrochemical impedance spectroscopy (EIS). In this study, we synthesized PANI using a chronoamperometric technique (galvanic) at 0.70 V for 900 s. Cyclic voltammetry revealed the redox couple between leucoemeraldine and emeraldine states, along with the specific capacitance measured by galvanostatic charge-discharge (GCD). Electrochemical impedance spectroscopy analysis allowed observe the potential window and resistive and capacitive responses between 0.2 and 0.7 V through Nyquist plots. Interestingly, the low-frequency pseudocapacitive analysis showed high specific capacitance at 0.2 V (emeraldine phase) and for benzoquinone and hydroquinone (intermediate phases). Complex capacitance analysis corroborates that the most capacitive potential, corresponding to emeraldine, achieved actual capacitances (C′) of 151 mF.cm⁻². Additionally, relaxation time constants were calculated, and the intersection points for complex power occurred at roughly 70 % for the most capacitive potentials. These results identify the potentials with capacitive and resistive characteristics, providing a deeper understanding of PANI's properties, which can help in future studies using polyaniline in electrochemical applications.