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Measurement of the Dependence of Interfacial Charge-Transfer Rate Constants on the Reorganization Energy of Redox Species at n-ZnO/H_2O Interfaces

Hamann, Thomas W. and Gstrein, Florian and Brunschwig, Bruce S. and Lewis, Nathan S. (2005) Measurement of the Dependence of Interfacial Charge-Transfer Rate Constants on the Reorganization Energy of Redox Species at n-ZnO/H_2O Interfaces. Journal of the American Chemical Society, 127 (40). pp. 13949-13954. ISSN 0002-7863. doi:10.1021/ja0515452. https://resolver.caltech.edu/CaltechAUTHORS:20170516-102143971

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Abstract

The interfacial energetic and kinetics behavior of n-ZnO/H_2O contacts have been determined for a series of compounds, cobalt trisbipyridine (Co(bpy)_3^(3+/2+)), ruthenium pentaamine pyridine (Ru(NH_3)_5py^(3+/2+)), cobalt bis-1,4,7-trithiacyclononane (Co(TTCN)_2^(3+/2+)), and osmium bis-dimethyl bipyridine bis-imidazole (Os(Me_2bpy)_2(Im)_2^(3+/2+)), which have similar formal reduction potentials yet which have reorganization energies that span approximately 1 eV. Differential capacitance vs potential and current density vs potential measurements were used to measure the interfacial electron-transfer rate constants for this series of one-electron outer-sphere redox couples. Each interface displayed a first-order dependence on the concentration of redox acceptor species and a first-order dependence on the concentration of electrons in the conduction band at the semiconductor surface, in accord with expectations for the ideal model of a semiconductor/liquid contact. Rate constants varied from 1 × 10^(-19) to 6 × 10^(-17) cm^4 s^(-1). The interfacial electron-transfer rate constant decreased as the reorganization energy, λ, of the acceptor species increased, and a plot of the logarithm of the electron-transfer rate constant vs (λ + ΔG°‘)^2/4λk_BT (where ΔG°‘ is the driving force for interfacial charge transfer) was linear with a slope of ∼ −1. The rate constant at optimal exoergicity was found to be ∼5 × 10^(-17) cm^4 s^(-1) for this system. These results show that interfacial electron-transfer rate constants at semiconductor electrodes are in good agreement with the predictions of a Marcus-type model of interfacial electron-transfer reactions.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/ja0515452DOIArticle
http://pubs.acs.org/doi/abs/10.1021/ja0515452PublisherArticle
ORCID:
AuthorORCID
Brunschwig, Bruce S.0000-0002-6135-6727
Lewis, Nathan S.0000-0001-5245-0538
Additional Information:© 2005 American Chemical Society. Received 10 March 2005. Published online 16 September 2005. Published in print 1 October 2005. We acknowledge the Department of Energy, Office of Basic Energy Sciences, for support of this work.
Funders:
Funding AgencyGrant Number
Department of Energy (DOE)UNSPECIFIED
Issue or Number:40
DOI:10.1021/ja0515452
Record Number:CaltechAUTHORS:20170516-102143971
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170516-102143971
Official Citation:Measurement of the Dependence of Interfacial Charge-Transfer Rate Constants on the Reorganization Energy of Redox Species at n-ZnO/H2O Interfaces Thomas W. Hamann, Florian Gstrein, Bruce S. Brunschwig, and Nathan S. Lewis Journal of the American Chemical Society 2005 127 (40), 13949-13954 DOI: 10.1021/ja0515452
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:77493
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:16 May 2017 18:45
Last Modified:15 Nov 2021 17:31

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