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Issue 12, 2011
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Kinetics of oxygen evolution at α-Fe2O3 photoanodes: a study by photoelectrochemical impedance spectroscopy

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Abstract

Photoelectrochemical Impedance Spectroscopy (PEIS) has been used to characterize the kinetics of electron transfer and recombination taking place during oxygen evolution at illuminated polycrystalline α-Fe2O3 electrodes prepared by aerosol-assisted chemical vapour deposition from a ferrocene precursor. The PEIS results were analysed using a phenomenological approach since the mechanism of the oxygen evolution reaction is not known a priori. The results indicate that the photocurrent onset potential is strongly affected by Fermi level pinning since the rate constant for surface recombination is almost constant in this potential region. The phenomenological rate constant for electron transfer was found to increase with potential, suggesting that the potential drop in the Helmholtz layer influences the activation energy for the oxygen evolution process. The PEIS analysis also shows that the limiting factor determining the performance of the α-Fe2O3 photoanode is electron–hole recombination in the bulk of the oxide.

Graphical abstract: Kinetics of oxygen evolution at α-Fe2O3 photoanodes: a study by photoelectrochemical impedance spectroscopy

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Publication details

The article was received on 05 Nov 2010, accepted on 14 Dec 2010 and first published on 13 Jan 2011


Article type: Paper
DOI: 10.1039/C0CP02408B
Phys. Chem. Chem. Phys., 2011,13, 5264-5270

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    Kinetics of oxygen evolution at α-Fe2O3 photoanodes: a study by photoelectrochemical impedance spectroscopy

    K.G. Upul Wijayantha, S. Saremi-Yarahmadi and L. M. Peter, Phys. Chem. Chem. Phys., 2011, 13, 5264
    DOI: 10.1039/C0CP02408B

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