We report on the development of the cyclic reciprocal derivative chronopotentiometry (CRDC) method with controlled alternating current to investigate the mechanisms of rapid electrochemical reactions. The proposed approach is based on the use of alternating current of industrial frequency. To obtain the Е - t response, we used a scheme which includes an electric chain consisting of a germanium diode and an adjustable source of constant voltage being parallel to the sensor electrodes. Digital analysis of the primary data allows us to obtain the following signal transformants: dE/dt-Е, dt/dE-E, dq/dE-E, I-E. Such an approach permits to observe the structurization of the response, which can be associated with the process stages. The modified CRDC method was applied to the oxidation of catechol and pyrocatechin violet dye on platinum microelectrodes and to the reduction of camphor, methionine, and methylene blue dye on a mercury dropping electrode. It was found that the anodic oxidation of catechol and its derivatives is accompanied by the peak structurization exhibited on the Сd - E dependences, indicating a two-stage process, while the Сd - E dependence of the pyrocatechin violet dye molecule, containing a catechol core, did not show any peak structurization. This can be explained by one-electron oxidation process with formation of a radical, which is similar to the Gomberg’s triphenylmethyl radical. This conclusion is also confirmed by our results of density functional theory (DFT) calculations for the corresponding dye, radical and dimer. The Сd - E dependence for camphor indicates the reaction-desorption EC mechanism. For methylene blue the cathode peak of very narrow half-width was obtained, which determines the dye aggregation and formation of dye nanophase on the mercury surface.
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