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Please use this identifier to cite or link to this item: http://dspace.library.iitb.ac.in/jspui/handle/100/13861

Title: Oxidation of Chloride Ion on Platinum Electrode: Dynamics of Electrode Passivation and its Effect on Oxidation Kinetics
Authors: PATIL, RS
JUVEKAR, VA
NAIK, VM
Keywords: OXYGEN OVERVOLTAGE MEASUREMENTS
POTENTIODYNAMIC M.P.P. METHOD
ANION ADSORPTION
BRIGHT PLATINUM
ACID SOLUTIONS
OXIDE-FILMS
ANODIC POLARIZATION
GROWTH-KINETICS
EVOLUTION
MECHANISM
Issue Date: 2011
Publisher: AMER CHEMICAL SOC
Citation: INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH,50(23)12946-12959
Abstract: Kinetics of oxidation of chloride ion is studied on both active platinum electrode and that undergoing transient passivation. Experiments are conducted in concentrated NaCl solution at rotating disk electrode. It is observed that on the active platinum electrode, oxidation is very fast, and hence the current density is controlled by the ohmic resistance of the solution. Electrode kinetics becomes important only when the electrode is passivated to a significant extent. Kinetics of chloride oxidation on the electrode undergoing passivation is modeled using the Butler-Volmer equation, in which the contribution from the ohmic resistance of the solution is incorporated. Two regimes of passivation are identified. The first is the fast regime corresponding to the formation of the platinum oxide monolayer. In this regime, the rate of passivation is first order in the concentration of the metal sites on the surface. In the slow passivation regime, the exchange current density for chloride oxidation is found to vary inversely with square root of time. This regime is modeled by considering unsteady diffusion of oxygen ions through the metal lattice. From this analysis it is concluded that the chloride oxidation current is almost totally contributed by a small fraction of the active metal sites which are continuously being regenerated as a result of diffusion of oxygen ions from the surface into the bulk of the metal.
URI: http://dx.doi.org/10.1021/ie200663a
http://dspace.library.iitb.ac.in/jspui/handle/100/13861
ISSN: 0888-5885
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