Raman spectroelectrochemical study of electrode reactions of hydroquinone at electrodes modified with Nile blue and other azine type redox mediators
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Electrooxidation of hydroquinone (HQ) to benzoquinone (BQ) has been studied by Raman spectroelectrochemistry at a gold electrode modified with adsorbed or electropolymerized layer of the redox dye Nile blue. Raman spectra were excited with 785 nm laser line. Reversible electrochemical oxidation of HQ proceeded at a midpoint potential of 0.43–0.45 V vs. Ag/AgCl in pH 1.0 solution. The formation of a reaction product BQ has been observed at a controlled electrode potential of 0.6 V by Raman scattering from the modified electrode. The formation of BQ appears to occur faster at a higher concentration of HQ. By comparing the data with our previous studies done with electrodes modified by the variety of azine class redox dyes Meldola blue, Neutral red, and Toluidine blue, it was concluded that the formation of a reaction product BQ could be observed by Raman spectroelectrochemistry only in absence of resonance Raman enhancement of surface attached dye, viz. at a sufficient long distance on the wavelength scale between the dye optical absorbance and laser line used for spectra excitation.
KeywordsRaman spectroscopy Spectroelectrochemistry Redox mediators Azine
- 18.Mažeikienė R, Niaura G, Eicher-Lorka O, Malinauskas A (2019) Raman spectroelectrochemical study of redox dye Nile blue adsorbed or electropolymerized at a gold electrode. Chemija 30:78–88Google Scholar