LowFrequency Electrochemical Impedance of Benzene
Oxidation on Anode of BoronDoped Diamond

V. V. Elkin^z and M. D. Krotova

Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia

Received June 25, 2012

Abstract—Kinetics of low–frequency adsorption of benzene oxidation products are studied in 0.5 M K₂SO₄
on an anode of boron–doped diamond. A combination of current polarograms and impedance with analysis of
the impedance spectroscopy in the frequency range of 0.05–10 Hz allowed studying in detail the mechanism of
adsorption oxidation of benzene under the conditions of competition between this process and the more anodic
process of oxygen evolution that is also based on adsorption. A frequency–polarization diagram of dependences
of characteristic frequencies (CFs) of adsorption and desorption stages on potential was obtained for the prod-
uct of benzene oxidation and oxygen–containing intermediate of the oxygen evolution reaction. Controlled
stages of coupled processes, potentials, and characteristic frequencies of the points of changes in the reaction
mechanism are determined: 0.22 Hz at 2.0 V for benzene oxidation; 0.63 Hz at 2.22V for oxygen evolution.
The potential of maximum adsorption of the organic substance is 2.15 V. The obtained results can be useful in
the studies of the mechanism of coupled reactions including organic and inorganic intermediate adsorbates.

Keywords: CVD diamond, anodic oxidation, benzene, electrochemical kinetics, impedance, differential capac-
itance, adsorption

DOI: 10.1134/S1023193513110050

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