Role of cyclic voltammetry in characterizing solids: natural and synthetic manganese oxide octahedral molecular sieves

Octahedral molecular sieves (OMS) having the todorokite (OMS-1) and hollandite (OMS-2) structures were used to modify carbon paste electrodes, and their cyclic voltammograms were recorded. The presence of Mn[sup 2+] in OMS-1 makes it electroactive; OMS-2 is not electroactive. Synthetic and natural t...

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Bibliographic Details
Published in:Chemistry of materials 1993-10, Vol.5 (10), p.1395-1400
Main Authors: De Guzman, Roberto N, Shen, Yan Fei, Shaw, Brenda R, Suib, Steven L, O'Young, Chi Lin
Format: Article
Language:English
Subjects:
400400 - Electrochemistry
ADSORBENTS
ALKALI METALS
ALKALINE EARTH METALS
BARIUM
CATIONS
CHALCOGENIDES
CHARGED PARTICLES
Chemistry
Electrochemistry
ELEMENTS
Exact sciences and technology
General and physical chemistry
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
IONS
Kinetics and mechanism of reactions
MAGNESIUM
MANGANESE
MANGANESE COMPOUNDS
MANGANESE OXIDES
METALS
MOLECULAR SIEVES
OXIDES
OXYGEN COMPOUNDS
POTASSIUM
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
VOLTAMETRY
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Summary:Octahedral molecular sieves (OMS) having the todorokite (OMS-1) and hollandite (OMS-2) structures were used to modify carbon paste electrodes, and their cyclic voltammograms were recorded. The presence of Mn[sup 2+] in OMS-1 makes it electroactive; OMS-2 is not electroactive. Synthetic and natural todorokites showed very similar cyclic volammetric responses despite the difference in tunnel counter cations. Natural todorokites may contain different tunnel counter cations such as Mg[sup 2+], Ba[sup 2+], and K[sup +], while synthetic todorokite was prepared with Mg[sup 2+] as the counter cation in the tunnels. The different tunnel counter cations such as Mg[sup 2+], Ba[sup 2+], and K[sup +] do not influence the electrochemistry of either synthetic or natural todorokites. This observation suggests that the observed electroactivity of synthetic and natural todorokite may be due to framework Mn[sup 2+]. Todorokite synthesized in the presence of Cu[sup 2+] (Cu-OMS-1) was also used to modify carbon paste electrodes. Results indicate that Cu[sup 2+] in the Cu-OMS-1 is electroactive and mobile, but cannot be completely removed, suggesting that Cu[sup 2+] is located in the tunnels of Cu-OMS-1. OMS-1 modified carbon paste electrodes show an enhancement in the signal for Cu[sup 2+] ion in solution over that of unmodified electrodes. Cu[sup 2+] can exchange reversibly into and out of the tunnels of OMS-1 during cyclic volammetric experiments. 32 refs., 14 figs., 3 tabs.
ISSN:0897-4756
1520-5002
DOI:10.1021/cm00034a006