In Situ Spectroelectrochemistry

Goal:

Identification of electrochemical reaction products in situ during the electrochemical reaction in contact with the electrolyte solution and under applied potential.

Method:

Fourier Transform Infrared (FTIR) Spectroscopy.

Problem:

Strong absorption of infrared radiation by the electrolyte solution and/or the electrode.

Solution:

Special measurement techniques.

System:

As an example, the oxidation of polyparaphenylenevinylene (PPV) in acetonitrile/tetrabutylammoniumhexafluorophosphate solution is shown. The figure shows a slow cyclic voltammogram obtained in the spectroelectrochemical cell. The full square indicates the potential of the reference spectrum, the open squares the potentials of the sample spectra, which are related to the reference spectrum. In this way difference spectra are obtained.
Click for a full view of the cyclic voltammogram.

Results:

During the oxidation reaction strong infrared bands appear. The broad band at high energy can be related to an electronic absorption, the bands in the vibrational range of the spectrum indicate the formation of charge carriers on the polymer chain.
Click for a full view of the in situ spectra.
Click for an animated view of the in situ spectra (about 1 MB !)
 

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