SEC-C Spectroelectrochemical Cell

Spectroelectrochemistry (SEC) is aimed at the investigation of electrochemical reaction mechanism and the interface structure between electrolyte solution and electrode. Remarkable progress in this field and related technology enables SEC to be applied in wide areas.
Nowadays, the relation between absorbance and potential for reversible or quasi-reversible system is theoretically elucidated, on which basis the analysis of electrochemical characteristics becomes possible for the system otherwise difficult with only the result of voltammogram.
Typical example is redox enzyme cytochrome c and methylene blue.

Comparison of 0.5 and 1.0 optical path length cell

The electrolysis stabilization time for the 0.5 mm optical path length cell is theoretically a half, compared with the 1.0 mm cell. It is the opposite, for the concentration, when the same result for the 1.0 mm cell is possible for a half of the concentration compared with the 0.5 mm cell. You could select the optical path length and the working electrode appropriate for your research purpose.

Comparison of the electrolysis reaction equilibrium time

For the comparison of the 0.5 and 1.0 optical path length cells, there is a difference between the theoretical and experimental values. It is in consequence of the experimental conditions.

Fig.1-1. Absorbance for electrolysis performed with 0.5 mm optical path length cell		Fig.1-2. Absorbance for electrolysis performed with1.0 mm optical path length cell
A 2 mM potassium ferrocyanide (K4[Fe(CN)6]) was subjected to an electrolysis reaction at 0.6 V until its stability, and 1 M KNO3 was used as a reference. The oxidation reaction was monitored by the comparison of the absorbance in function of the time at wavelengths of 420 and 300 nm.

Optical path length 1.0 mm cell

 

 

The optical path length 1.0 mm is most suitable for basic spectrum electrochemistry measurements. Theoretically, it is possible to get the same result as for 0.5 mm with a half concentration sample.

Optical path length 0.5 mm cell

 

 

The optical path length 0.5 mm has an electrolysis time shorter than 1.0 mm cell. The stability short time for the electrolysis makes possible to have a stable result as for, measurement of the high volatile organic solvent, detection of the unstable electrolysis products, and others.

∗There is a specific working electrode for 0.5 mm optical path length. The working electrode for 1.0 mm optical path length can not be used in 0.5 mm optical path length quartz cell.

Measurement example using cuvette type spectroelectrochemical cell

UV-visible absorption spectrum and absorbance of the product of the electrode reaction, performed with optically transparent electrode (OTE), were measured. Gold or Platinum mesh electrode was used as an OTE. Cyclic voltammetry and Absorbance of the 2 mM potassium ferricyanide, as the reference of the absorbance, performed in a SEC-C Thin Layer Quartz Glass Spectroelectrochemical cell are shown below (Figure 2-1, 2-2).

Fig.2-1. Cyclic voltammetry for 2 mM potassium ferricyanide.		Fig.2-2. Absorption spectra of the electrolytic balance for 2 mM potassium ferricyanide electrolyzed at different potential.

Simultaneous measurements of the cyclic voltammetry and absorbance as well a constant potential electrolysis measurement were also performed. The electrolysis, reduction (Figure 3-1) and oxidation (Figure 3-2), of the potassium ferrocyanide solution are shown below.

Fig.3-1. Absorbance changes for the reduction of the potassium ferrocyanide.		Fig.3-2. Absorbance changes for the oxidation of the potassium ferricyanide.

Flow cell

Spectroelectrochemical flow cell