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Cobalt Additives Influence on Phase Composition and Defect Structure of Manganese Dioxide Prepared from Fluorine Containing Electrolytes

100%

Sokolsky G., Ivanov S., Ivanova N., Boldurev Y., Kobulinskaya O., Demchenko M.

issue 1

86-90

Manganese dioxide samples were prepared from fluorine containing electrolytes with additives of Co^{2+} ions. Atomic absorption spectroscopy, thermogravimetric analysis, X-ray diffraction, scanning electron microscopy with energy dispersive X-ray analysis were the methods of the samples characterisation. Manganese dioxide at the presence of cobalt forms nanosized ramsdellite structure crystallites of mostly needle-like morphology with significant content of hydroxide groups. The main phase state in manganese dioxide samples obtained at the presence of cobalt is γ-MnO_{2} with ramsdellite structure and low content of intergrowth defects. The sample doped both with lithium and cobalt can be indexed to a hollandite-type structure (tetragonal; space group I4/m) of α-MnO_{2}.

ORR Electrocatalysis on Cr³⁺, Fe²⁺, Co²⁺-Doped Manganese(IV) Oxides

100%

Sokolsky G., Zudina L., Boldyrev E., Miroshnikov O., Gauk N., Kiporenko O.

Acta Physica Polonica A

2018

vol. 133

issue 4

1097-1102

The ionic dopant additives have different mechanisms of their influence upon MnO₂ electrocrystallisation process and depending on dopants added the following polymorphs are stabilised: α -MnO₂ (hollandite, I4/m) - NH₄⁺; γ -MnO₂ (ramsdellite, Pbnm) - Co²⁺, Fe²⁺; layered polymorph δ -MnO₂ (birnessite, C2/m) - Cr³⁺. The defect states of intergrowth method in ramsdellite matrix and twinning, OH groups studied by X-ray diffraction and the Fourier transform infrared mtehod, respectively, indicate their high content in case of Fe²⁺ and Co²⁺-doped manganese dioxide. CVA oxygen reduction reaction peaks were established after experiments in alkaline electrolytes and dioxygen (argon, air) atmosphere. Activity of doped samples studied is comparable with other published data. Both doped with Co²⁺ and Fe²⁺ samples display maximal currents and some distinctive features in oxygen reduction reaction.

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2 Acta Physica Polonica A

1 2018

1 2010

2 Sokolsky G.

1 Boldurev Y.

1 Boldyrev E.

1 Demchenko M.

1 Gauk N.

1 Ivanov S.

1 Ivanova N.

1 Kiporenko O.

1 Kobulinskaya O.

1 Miroshnikov O.

1 Zudina L.

Search results

Cobalt Additives Influence on Phase Composition and Defect Structure of Manganese Dioxide Prepared from Fluorine Containing Electrolytes

ORR Electrocatalysis on Cr³⁺, Fe²⁺, Co²⁺-Doped Manganese(IV) Oxides