engleski

Impedance study of thin PANI layers of different thicknesses

The effect of the polyaniline (PANI) layer thickness on impedance characteristics has been investigated. It has been found that PANI layer thickness has a significant influence on the impedance response of the PANI layer. The impedance response of PANI layers, presented in the low frequency region of Nyquist spectra, indicates an increase of real and imaginary impedance values as PANI layer thickness increases. Presentations of EIS data in Bode diagrams suggest two separate processes detected in the low and in the high frequency regions, respectively. The model used to analyze EIS data in terms of an electrical equivalent circuit resulted in PANI capacitance and PANI resistance values used, to calculate time constants for each of the processes. The EIS parameters, obtained from EIS data analysis, were used to interpret processes taking place inside PANI and at the PANI | electrolyte interface. The two major processes have been identified. The EIS analysis parameters are used to explain the changes of the PANI layer structure and of the PANI | electrolyte interface. In this work the total PANI layer capacitance, calculated from PANI EIS parameters, was compared to PANI current obtained by scanning the layer in the supporting electrolyte. The total PANI layer capacitance, in the potential region where the conductive form of PANI is present, was calculated as a function of two capacitances in series.

electrosynthesis ; PANI ; electrochemical impedance spectroscopy ; polymer layer structure

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