Polarization Characteristics of Porous Electrode Systems with Adsorbed Intermediates Participating in the Electrode Reaction

Tilak, BV and Venkatesh, S and Rangarajan, SK (1989) Polarization Characteristics of Porous Electrode Systems with Adsorbed Intermediates Participating in the Electrode Reaction. In: Journal of the Electrochemical Society, 136 (7). pp. 1977-1982.

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Abstract

Current-potential relationships are derived for porous electrode systems following a homogeneous model and whenadsorbed intermediates participate in the electrode reaction. Limiting Tafel slopes were deduced and compared with thecorresponding behavior on planar electrode systems. The theoretical results showed doubling of Tafel slopes when theslow-step is a charge-transfer reaction and a nonlogarithmic current-voltage behavior when the slow-step is a chemical reaction.Comparison of the experimental results with theory for the case of oxygen reduction on carbon surfaces in alkalinemedia indicates that a slow chemical reaction following the initial charge-transfer reaction to be the likely rate-controllingstep. Theoretical relationships are utilized to determine the exchange current density and the surface coverage by the adsorbedintermediates during the course of oxygen reduction from alkaline solutions on "carbon." Tafel slope measurementson planar and porous electrodes for the same reaction are suggested as one of the diagnostic criteria for elucidatingthe mechanistic pathways of electrochemical reactions.

Item Type:	Journal Article
Publication:	Journal of the Electrochemical Society
Publisher:	The Electrochemical Society
Additional Information:	Copyright of this article belongs to The Electrochemical Society.
Keywords:	Electrochemical electrodes,adsorbed layers,porosity,chemical reactions,reaction kinetics,electric properties.
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	17 Aug 2010 04:14
Last Modified:	19 Sep 2010 06:14
URI:	http://eprints.iisc.ac.in/id/eprint/31267

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