Dresden 2009 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 40: POSTERS Electronic and Optical Properties

CPP 40.5: Poster

Donnerstag, 26. März 2009, 17:00–19:30, P3

Influence of electrochemical cell construction at impedance spectroscopy measurements — Matthias Haase, •Patryk Hallek, and Volker Buck — University Duisburg-Essen, Department of Technical Physics, Germany

The degradation of materials which follow-up to corrosion is one of the most important problems. Particular identification of processes, which take place at the surface of materials, helps to improve the properties of anticorrosion coatings. One of the best method to study corrosions processes is the Electrochemical Impedance Spectroscopy (EIS). This method gives the possibility to recognize very well the change of the surface properties through corrosion products, but a wrong layout of the electrochemical cell can take strong influence at the results.

This work describes the influence of the construction of an electrochemical cell at the measured impedance spectra. For the measurements a three electrode system was established by using either a glass and a plastic chamber. A platinum foil was used as a counter electrode. As a reference electrode and pseudo-reference electrode we took a silver chloride electrode or a platinum rod, respectively.

The measured spectra show a strong interaction between the three electrodes. The impedance plots contain several artifacts in form of capacitive and inductive arcs. This arcs are not correlated with the corrosion process, but they influence on the correct interpretation of the results and choice of an equivalent electric network. The experiments shows that this effects can be minimized by the optimization of the electrochemical cell construction.