title: A comparison between interfacial electron-transfer rate constants at metallic and graphite electrodes.
abstract: The Fermi golden rule formalism has been used to derive the rate constant for interfacial electron transfer from a semimetallic electrode, such as highly ordered pyrolytic graphite (HOPG), to a redox couple in solution. A simple expression is presented that semiquantitatively relates the electron-transfer rate constant at a semimetallic electrode to that at a metallic electrode. The approach allows for the estimation of the value of the rate constant for interfacial charge transfer to nonadsorbing outer-sphere redox species at semimetallic electrodes. Rate constants for interfacial electron transfer for a variety of one-electron redox couples at semimetallic electrodes have been calculated relative to the rate constant of the ferrocenium/ferrocene redox couple at a gold electrode. Good agreement is found, in general, between the calculated and observed rate constants.
authors.affiliation: Beckman Institute and Kavli Nanoscience Institute, Division of Chemistry and Chemical Engineering, 210 Noyes Laboratory, 127-72, California Institute of Technology, Pasadena, 91125, USA.
authors.forename: William J
authors.initials: WJ
authors.lastname: Royea
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Hamann
authors.forename: Bruce S
authors.initials: BS
authors.lastname: Brunschwig
authors.forename: Nathan S
authors.initials: NS
authors.lastname: Lewis