Impedance spectroscopy of oxidized polyaniline and poly(o-ethoxyaniline) thin film modified Pt electrodes

Analysis of high-frequency distortions in impedance spectra of conducting polyaniline film modified Pt-electrode measured with different cell configurations

“…Overlapping between various impedance responses was found particularly evident in measurements of either highly resistive WE branch (electrode and solution of low conductivity) [3,4,7,8], or highly conductive WE branch (electrode and solution of high conductivity) [9][10][11][12][13]. In both cases, distortions originating not only from reference (RE) and counter (CE) electrodes and their geometrical arrangement [3,4,7,8,13], but also from measuring instrumentation and wirings [9][10][11], have been recognized as main sources of additional impedances termed as experimental artefacts.…”

“…In already presented impedance spectra of low impedance and highly capacitive WE such as conducting form of polyaniline (PANI) film modified electrodes and/or PANI membranes in acidic solutions, relatively high extent of distortions could be noticed in high frequency parts of impedance spectra measured in either conventional three-electrode cell [16][17][18], in three-electrode cell with RE connected with pseudo-reference electrode (PRE) [9,10,12,13], or in four-electrode cell with two RE's [17,19]. Since in the case of highly capacitive and low impedance WE, presence of parasitic impedances and/or reflections of RE and CE in measured impedance spectra could hardly be avoided, even after using PRE placed close to RE [9,10,12,13], it seems to be of high importance to distinguish and separate their frequency response from the frequency response of impedance branch containing conducting PANI film WE. Characterization, distinguishing and separation of overlapping impedances at high frequencies might be relevant not only for recognition and characterization of all processes influencing short-time response of conducting PANI films what is important for a number of conducting PANI films applications [20], but for definition of physical origins and possible control of the content of experimental artefacts in impedance measurements too.…”

Electrochemical Impedance Spectroscopy (EIS) for Polymer Characterization

“…The CPE has been used to describe both the double-layer capacitance and the low-frequency pseudocapacitance as well as the diffusion impedance [19,20,22,23,60,83,88,108,119,120,172]:…”

“…Essentially, there are two different approaches, which are called ''homogeneous'' or ''uniform'' [12,29,40,62,69,70,83,88,107,112,130,177,178] and ''porous medium'', ''heterogeneous'', or ''distributed'' models [5,6,21,52,58,83,93,132,146,149,153,154,158,160], respectively, based on two different perceptions regarding the structure of the surface polymer layers or membranes (Figure 3.6). …”

“…Within the alternative approach, the film is considered as a porous medium [6,52,57,58,83,138,146,147,149,158,160]. Physically, it represents a porous membrane that includes a matrix formed by the conducting polymer and pores filled with an electrolyte.…”