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BY-NC-ND 3.0 license Open Access Published by De Gruyter June 2, 2014

Die Rolle von Redoxmediatoren bei der Korrosion des Bleidioxids in HBF4 The Role of Redox Mediators in the Corrosion of Lead Dioxide in HBF4

  • Fritz Beck

Abstract

Layers of lead dioxide, electrochemically deposited on graphite filled polypropylene, corrode rather slowly in 1 m HBF4/1 m Pb (BF4)2 under oxygen evolution with an equivalent current den­ sity of 1 - 4 μA/cm2. The rate of corrosion may be accelerated by a factor of 100 by localized cell action with graphite. In the presence of reducing agents like Fe++ or V+++, a significant acceleration occurs as well, which is limited by transport to the surface of the oxide. The oxidized component may be regenerated continously at a lead counterelectrode. However, hydroquinone is partially oxidized irreversibly beyond the quinone stage, and Tl+ is partially incorporated as Tl2O3.

Chemically prepared lead dioxide powders corrode slowly in 1 m HBF4 as well and tend to passivate. The passivation is only partially avoided by collision with a lead surface. However, rapid dissolution occurs in the presence of reducing agents like Fe++. The acceleration is shown to exceed the stoichiometric conversion of the redox mediator. Additional measurements with Pb3O4 powders have been performed. Consequences in regard to the lead tetra-fluoborate accumulator are discussed.

Received: 1977-6-8
Published Online: 2014-6-2
Published in Print: 1977-9-1

© 1946 – 2014: Verlag der Zeitschrift für Naturforschung

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

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