Electrochemical investigations on the kinetics of the growth of PbO2 layers on lead

✍ Scribed by Jürgen P. Pohl; Wilfried Schendler

• Publisher: Elsevier Science
• Year: 1984
• Tongue: English
• Weight: 763 KB
• Volume: 13
• Category: Article
• ISSN: 0378-7753
• DOI: 10.1016/0378-7753(84)87081-0

✦ Synopsis

Potentiostatic

polarization measurements of the growth of lead dioxide layers on lead electrodes in sulfuric acid solutions have been made. During an initial period a closed PbOz layer is formed anodically on the lead surface. Subsequent growth takes place according to a parabolic rate law with a "parabolic tarnishing constant", kPbO,, in the order of magnitude of lo-" cm* s-i. This is in agreement with the assumption that the rate-determining step of the growth reaction is the diffusion of oxygen (O*-ions and electrons) through the oxide layer from the Pb02/electrolyte interface, where oxygen is incorporated anodically into the solid phase, to the internal phase boundary, where the reaction with lead takes place. Using the fact that the chemical potentials of oxygen in the Pb02 layer at the phase boundaries are fixed by the electrode potential and by the equilibrium with the internal neighbouring phase, respectively, a mean component diffusion coefficient, ~,~-(Pb02), of oxygen ions in lead dioxide has been calculated from kPbO,. ,Dol-( Pb02) is in the order of magnitude of lo-l3 cm* s-l.

Zusammenfassung

Das Wachstum von Bleidioxid-Schichten auf Bleielektroden in schwefelsauren Lijsungen wurde mit Hilfe potentiostatischer Polarisationsmessungen untersucht.