Electrochemical oxidation of Mn(OH){sub 2} in alkaline media

Journal Article · Fri Aug 01 04:00:00 EDT 1997 · Journal of the Electrochemical Society

DOI:https://doi.org/10.1149/1.1837867· OSTI ID:536453

Cha, D K ^[1]; Park, S M ^[2]

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1. Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Chemistry
2. Pohang Univ. of Science and Technology (Korea, Republic of)

Redox transformations of the Mn(II)/Mn(III) and Mn(II)/Mn(IV) pairs have been studied by transient electrochemical, spectroelectrochemical, and impedance measurements in alkaline solutions at a manganese electrode. The Mn(0)/Mn(II) and Mn(II)/Mn(III) pairs, which have not been clearly identified hitherto in the literature, have been observed using these techniques. A species observed at 285 nm during oxidation of the Mn(OH){sub 2}-covered manganese electrode was assigned to MnOOH. This species eventually led to passive films whose major component is MnO{sub 2} absorbing at about 400 nm. An accumulation of the passive films was observed at longer electrolysis times. Electrochemical impedance measurements were used to construct a Tafel plot for the manganese oxidation. The polarization resistance reached a minimum at about + 0.17 V vs Ag{vert_bar}AgCl (saturated KCl) without oxygen evolution. Some kinetic information including resistance-capacitance time constants for the oxidation reaction and an exchange current density are also reported.

• Sponsoring Organization: USDOE, Washington, DC (United States)
• OSTI ID: 536453
• Journal Information: Journal of the Electrochemical Society, Journal Name: Journal of the Electrochemical Society Journal Issue: 8 Vol. 144; ISSN JESOAN; ISSN 0013-4651
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CATHODES
ELECTRIC BATTERIES
ELECTROLYSIS
MANGANESE
MANGANESE HYDROXIDES
MANGANESE OXIDES
OXIDATION
PASSIVATION