DOI: https://doi.org/10.15421/081515

The peculiarities of electrooxidation of Mn2+ to MnO2 in acetate electrolyte

Viktor F. Vargalyuk, Veronika V. Poltavets, Ludmila V. Shevchenko

Abstract


The results of investigation of Mn2+ electrooxidation mechanism in the presence of acetate ions have been presented. The kinetic measurements were supplemented by quantum-chemical modeling. The calculated value of the redox potential of [Mn(H2O)5Ac]+/[Mn(H2O)5Ac]2+ system was compared with experimental data obtained at pH 5.2. The similar values have given a reason to assume the direct electrooxidation of ion Mn2+ to Mn3+ like complex [Mn(H2O)5Ac]+. The process occurs according to inner-sphere mechanism due to direct contact of the complex with the electrode through the carboxyl group. The quantum-chemical calculations have shown the impossibility of elimination of second electron without considerable reorganization of the complex [Mn(H2O)5Ac]2+. The final product of electrooxidation of Mn2+ acetate complex, manganese dioxide, was formed as a result of [Mn(H2O)5Ac]2+ disproportionation with subsequent hydrolysis of the [Mn(H2O)5Ac]3+ complex. In weakly acidic solution (pH above 4) due to reducing the number of [Mn(H2O)5Ac]+ complexes, electrooxidation of manganese ions were occurred by a similar mechanism to the acid sulphate solution, i. e. by radicals, produced by electrooxidation of water molecules.

Keywords


Mn2+ acetate complexes; electrooxidation; quantum-chemical modeling

References


Brenet, J. P. (1979). Electrochemical behavior of metallic oxides. J. Pover Sources, 4, 183–190.

Adelchani, H., & Ghaemi M. (2009). Influence of the solution pH on the nanostructural and electrochemical performance of electrolytic manganese dioxide. J. Alloys Compd., 481, 446–449.

Clarke, C. J., Browning, G. J., & Donne, S. W. (2006). An RDE and RRDE study into the electrodeposition of manganese dioxide. Electrochim. Acta., 51, 5773–5784.

Qu, D. Y., Bai, L., Castledine, C. G., Conway, B. E., & Adams, W. A. (1994). Spectro-electrochemical studies on production and role of soluble Mn(III) species in discharge and recharge of various MnO2 cathode materials. J. Electroanal. Chem., 365, 247–259.

Vargalyuk, V. F., & Poltavets, V. V. (2015). [Electro-oxidation of Mn2 + ions at a platinum electrode]. Suchasni problemi elektrohimii: osvita, science, virobnitstvo – Modern problems of electrochemistry: education, science and industry, 143–144 (in Ukrainian).

Patrushev, V. V., Kononov, Y. S., & Stop, S. W. (2002). Russian Patent No. RU 2193527 C1. Institute of Chemistry and Chemical Technology.

Serdyuk, V. A., & Vargalyuk, V. F. (2008). [Evaluation of reliability of quantum chemical calculations of the electronic transitions in aqua complexes of transition metals]. Russ. J. Electrochem, 44(10), 20–27 (in Russian).

Ravdel, A. A., & Ponomareva, A. M. (Ed.). (1983). [A quick reference physico-chemical variables]. Leningrad, USSR: Chemistry (in Russian).

Rossoti, F., & Rossoti, H. (1965). [Determination of stability constants and other equilibrium constants in solutions]. Moskow, USSR: Mir (in Russian).


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