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Electrode processes and charge transport in bulk redox conducting inorganic solids

✍ Scribed by Pawel J. Kulesza; Zbigniew Galus


Publisher
Elsevier Science
Year
1997
Tongue
English
Weight
655 KB
Volume
42
Category
Article
ISSN
0013-4686

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✦ Synopsis


Two different methods for solid-state electrochemical measurements in the absence of liquid electrolyte are discussed. The simplest approach is based on a two-electrode sandwich cell (without reference electrode), and it is suitable for ionically-conducting materials containing stable and chemically identifiable, mixed-valence redox sites (eg Fe(III,II) in Prussian Blue or Berlin Green). The second two-electrode design utilizes an ultramicrodisk working electrode which faces a large surface area silver-disk semireference/counter electrode. In order to discuss usefulness and limitations of these methods, we consider the following inorganic materials: Prussian Blue, Berlin Green, and silicotungstic acid single crystals. These structures contain mobile countercations (hydrated K+ or H+) in concentrations extensive enough to support diffusive transport of electrons hopping between Fe(III,II) or W(VI,V) centers (redox conduction). In the latter case, combination of potential step measurements in short-time and long-time experimental regimes provides an absolute electroanalytical method for determinations of redox centers and an effective diffusion coefficient for charge propagation.


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