Document Detail


Electrochemical proton-coupled electron transfer of an osmium aquo complex: theoretical analysis of asymmetric tafel plots and transfer coefficients.
MedLine Citation:
PMID:  20067257     Owner:  NLM     Status:  PubMed-not-MEDLINE    
Abstract/OtherAbstract:
Electrochemical proton-coupled electron transfer of an osmium aquo complex attached to a self-assembled monolayer on a gold electrode is studied with a recently developed theoretical formulation. The calculated hydrogen/deuterium kinetic isotope effect for the standard rate constant, the cathodic transfer coefficient at zero overpotential, and the Tafel plot are in excellent agreement with experimental data. The input quantities to the heterogeneous rate constant expressions were calculated with density functional theory in conjunction with dielectric continuum models, and no parameters were fit to experimental data. The theoretical calculations indicate that the asymmetry of the Tafel plot and the deviation of the transfer coefficient at zero overpotential from the standard value of one-half arise from the change in the equilibrium proton donor-acceptor distance upon electron transfer. The direction of the asymmetry and deviation from one-half is determined by the sign of this distance change, and the magnitude of these effects is determined by the magnitude of this distance change, as well as the reorganization energy and the distance dependence of the overlap between the initial and final proton vibrational wave functions. This theory provides experimentally testable predictions for the impact of specific system properties on the qualitative behavior of the Tafel plots.
Authors:
Michelle K Ludlow; Alexander V Soudackov; Sharon Hammes-Schiffer
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of the American Chemical Society     Volume:  132     ISSN:  1520-5126     ISO Abbreviation:  J. Am. Chem. Soc.     Publication Date:  2010 Feb 
Date Detail:
Created Date:  2010-01-27     Completed Date:  2010-04-05     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7503056     Medline TA:  J Am Chem Soc     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1234-5     Citation Subset:  -    
Affiliation:
Department of Chemistry, 104 Chemistry Building, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
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