Chlorine Evolution Reaction on RuO sub(2)(110): Ab initio Atomistic Thermodynamics Study - Pourbaix Diagrams

Constrained ab initio thermodynamics in the form of a Pourbaix diagram can greatly assist kinetic modeling of a particular electrochemical reaction such as the chlorine evolution reaction (CER) over RuO sub(2)(110). Pourbaix diagrams reveal stable surface structures, as a function of pH and the pote...

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Bibliographic Details
Published in:Electrochimica acta 2014-02, Vol.120, p.460-466
Main Authors: Exner, Kai S, Anton, Josef, Jacob, Timo, Over, Herbert
Format: Article
Language:English
Subjects:
Capping
Chlorine
Evolution
Pourbaix diagrams
Surface chemistry
Surface structure
Thermodynamics
Online Access:Get full text
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Summary:Constrained ab initio thermodynamics in the form of a Pourbaix diagram can greatly assist kinetic modeling of a particular electrochemical reaction such as the chlorine evolution reaction (CER) over RuO sub(2)(110). Pourbaix diagrams reveal stable surface structures, as a function of pH and the potential. The present DFT study indicates that the Pourbaix diagram in the CER potential region above 1.36 V and pH values around zero is dominated by a stable surface structure in which all coordinatively undercoordinated Ru sites (Ru sub(cus)) are capped by on-top oxygen (O sub(ot)). This oxygen saturated RuO sub(2)(110) surface is considered to serve as the catalytically active phase in the CER, quite in contrast to the heterogeneously catalyzed HCl oxidation (Deacon process), for which the active RuO sub(2)(110) surface is mainly covered by on-top chlorine. The active sites in the CER are suggested to be Ru sub(cus)O sub(ot) surface complexes, while in the Deacon process both undercoordinated surface Ru and oxygen sites must be available for the activation of HCl molecules.
ISSN:0013-4686
DOI:10.1016/j.electacta.2013.11.027