Experimental estimate of the electron-tunneling distance for some outer-sphere electrochemical reactions

Joseph T Hupp, Michael J. Weaver

Research output: Contribution to journalArticle

58 Citations (Scopus)

Abstract

Estimates of the reaction zone thickness over which electron tunneling can effectively occur for the outer-sphere electrochemical reduction of some Cr(III) complexes are obtained by comparing the observed work-corrected rate constants with unimolecular rate constants for the electroreduction of structurally similar surface-bound Cr(III) reactants. Effective reaction zone thicknesses of ca. 0.1-0.3 and ca. 5 Å are obtained for outer-sphere electron transfer with Cr(III) reactants containing predominantly aquo or ammine ligands, respectively. This indicates that the former reactions are marginally nonadiabatic whereas the latter are decidedly adiabatic at their respective planes of closest approach. These findings are compatible with the greater reactant-electrode separation distances previously noted for Cr(III) aquo relative to ammine complexes resulting from the more extensive hydration sheath surrounding the former reactants. Comparisons with recent calculates performed for some outer-sphere homogeneous reactions suggest that efficient electron tunneling takes place over roughly comparable distances at metal-electrolyte interfaces and in bulk solution.

Original languageEnglish
Pages (from-to)1463-1467
Number of pages5
JournalJournal of Physical Chemistry
Volume88
Issue number8
Publication statusPublished - 1984

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Electron tunneling
electron tunneling
ammines
Rate constants
estimates
Hydration
Electrolytes
Metals
Ligands
sheaths
hydration
electron transfer
Electrodes
Electrons
electrolytes
ligands
electrodes
metals

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Experimental estimate of the electron-tunneling distance for some outer-sphere electrochemical reactions. / Hupp, Joseph T; Weaver, Michael J.

In: Journal of Physical Chemistry, Vol. 88, No. 8, 1984, p. 1463-1467.

Research output: Contribution to journalArticle

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