Charge transfer rate constants for the reduction of cobaltocenium at accumulated nSi electrodes

A theoretical description of heterogeneous charge transfer rate constants has been developed for accumulated semiconductor electrodes in contact with outer sphere redox couples. Analysis of the rate constants using a Fermi Golden Rule formalism in a non-adiabatic electron transfer framework has facilitated a theoretical comparison between the rate constants of metal and accumulated semiconductor electrodes in contact with a common electrolyte-redox couple solution. Chronoamperometric measurements of nSi electrodes in contact with CH3OH-cobaltocenium (COCp2)+-CoCp2 have been performed to investigate these predictions experimentally. A standard rate constant, k°, of (2–4) × 10−2 cm S−1 was obtained for nSi/CH3OH-CoCp2+0 contacts, while the CoCp2+0 redox couple was found to be electrochemically reversible (k° > 0.1 cm s−1) at Hg electrodes under the same conditions.