Electrochemistry of porous and crystalline silicon electrodes in methylviologen solutions

Ernst S. Kooij, R.W. Despo, F.P.J. Mulders, J.J. Kelly

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From measurements using stationary and rotating disc and ring-disc electrodes, it is concluded that the reduction reactions of the divalent methylviologen cation MV2+ (to MV+· and MV0) proceed via the conduction band of both porous and crystalline silicon. The product of the second reduction step (MV0) forms a blocking layer on the electrode. The oxidation reactions of MV0 and MV+· take place by electron injection into the conduction band of n-type crystalline silicon. From the current-potential characteristics it follows that MV+· is also able to inject electrons into porous silicon formed on an n-type electrode. At p-type porous silicon, electroluminescence is observed as a result of radiative recombination of holes (majority carriers) with electrons (minority carriers) injected into the porous structure during oxidation of MV+·. Introducing ethanol into the solution leads to changes in the current-potential characteristics, which are explained by the solubility of MV0 in these solutions. The current-potential characteristics are considered on the basis of the position of the band edges, as deduced from impedance measurements, and differences between crystalline and porous silicon are discussed.
Original languageUndefined
Pages (from-to)139-146
JournalJournal of electroanalytical chemistry
Issue number1-2
Publication statusPublished - 1996


  • IR-75167

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