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

Vìsnik Dnìpropetrovsʹkogo Unìversitetu: Serìâ Hìmìâ

Viktor F. Vargalyuk¹  Ludmila V. Shevchenko¹  Veronika V. Poltavets¹ 

[1] Oles Honchar Dnipropetrovsk National University, 72 Gagarin Ave., Dnipropetrovsk 49010;

关键词: Mn2+ acetate complexes;    electrooxidation;    quantum-chemical modeling;   

DOI  :  10.15421/081515

来源: DOAJ

【 摘 要 】

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.

【 授权许可】

Unknown