Impedance spectroscopy and other electrochemical in-situ investigations of the phosphating process

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

“…A Pt wire (∼0.07 cm 2 in superficial area) was applied as PRE and in an order to avoid additional content of experimental artefacts involved by outside position of PRE versus RE [13], PRE was similarly to [4,7,24] placed within HL capillary of RE.…”

“…Working with highly capacitive WE such as conducting form of PANI film modified Pt electrode in solutions of high conductivity, however, it has been found that Pt-probe PRE connected with different C c and placed outside RE, generated certain content of "new" experimental artefacts in high frequency parts of impedance spectra, including formation of uneven inductive/resistive load to Z x [13]. To avoid these detrimental effects that were primarily related to an outside position of PRE [13], in the present experiments PRE was placed within HL capillary of RE [4,7,24], forming RE/PRE Table 5 Impedance parameter values of conducting PANI modified Pt electrode in 0.5 and 0.05 mol dm −3 H 2 SO 4 resulted from CNLS fittings of denoted impedance spectra from Figs. 2 and 4 to Eq.…”

“…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. Although impedance measurements in two-electrode configuration are generally free from experimental artefacts caused by electrical couplings between electrodes [1,5,6,14], some contributions from stray capacities and inductivities were found pronounced in measurements of (very) high and (very) low impedance cells, respectively [6,14,15].…”

Electrocatalysis in water electrolysis with solid polymer electrolyte

“…Grzeszczuk et al [144] measured a similar pseudo inductive loop for the HER on nanoparticles of Pt incorporated into a polyaniline film on a polished glassy carbon disk measured in HCl aqueous solution. This type of inductive behaviour has usually been addressed to phenomena as intrinsic capacitances of the reference electrode, interfacial relaxation and adsorption phenomena [145].…”

Polarization and impedance studies on zinc phosphate coating developed using galvanic coupling

“…10,11 AC impedance studies involve the measurement of the charge transfer resistance (R ct ), the double layer capacitance (C dl ) and the Warburg impedance (Z w ), the parameters that constitute the proposed equivalent electrical circuit model in correlation with the behavior of coated system in a corrosive environment. Literature reports on the evaluation of phosphate coatings [17][18][19] suggest that the corrosion behavior of phosphate coatings in contact with the corrosive medium (3.5% NaCl) can be explained on the basis of a porous film model since the electrolyte/ coating-metal interface approximates such a model. Accordingly, the phosphated substrates are considered as partially blocked electrodes when they come in contact with 3.5% NaCl solution.…”