Electron Transfer Rate Constants for Majority Electrons at GaAs and GaInP2 Semiconductor-Liquid Interfaces

Andreas Meier, Shyam S. Kocha, Mark C. Hanna, Arthur J. Nozik, Kerstin Siemoneit, Rolf Reineke-Koch, Rüdiger Memming

Research output: Contribution to journalArticlepeer-review

25 Scopus Citations


Current-voltage and impedance measurements have been conducted at different n-type III-V semiconductor electrodes in acetonitrile as a function of the concentration of cobaltocenium-cobaltocene (Co(Cp)2+/0), an outer-sphere and fast redox couple. The measurements reveal that the interfacial chemistry, especially as affected by etchants, has a very strong influence on the kinetics of the charge transfer reaction. According to our impedance analysis, which covered a frequency range between 10 Hz and 400 kHz, movement of the energy bands in the onset region of the forward current can be excluded for this system. For this reason a comparatively simple model can be used for the evaluation of the second-order rate constants for the electrochemical charge transfer reaction across the semiconductor-electrolyte interface. The combined analysis of the steady-state current/potential curves and the impedance spectra show that for the semiconductor electrode-electrolyte systems we have studied, the electron transfer rate constant ranges from about mid10-10 cm4 s-1 to 10-17 cm4 s-1. The former value is unusually large and is over 6 orders of magnitude greater than the maximum possible rate constant predicted and reported by other workers; possible explanations are discussed.

Original languageAmerican English
Pages (from-to)7038-7042
Number of pages5
JournalJournal of Physical Chemistry B
Issue number36
StatePublished - 1997

NREL Publication Number

  • NREL/JA-450-23890


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