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New insights into water splitting at mesoporous α-Fe2O3 films: a study by modulated transmittance and impedance spectroscopies


Reference:

Cummings, C. Y., Marken, F., Peter, L. M., Upul Wijayantha, K. G. and Tahir, A. A., 2012. New insights into water splitting at mesoporous α-Fe2O3 films: a study by modulated transmittance and impedance spectroscopies. Journal of the American Chemical Society, 134 (2), pp. 1228-1234.

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    Official URL:

    http://dx.doi.org/10.1021/ja209530s

    Abstract

    Thin mesoporous films of α-Fe 2O 3 have been prepared on conducting glass substrates using layer-by-layer self-assembly of ca. 4 nm hydrous oxide nanoparticles followed by calcining. The electrodes were used to study the oxygen evolution reaction (OER) in the dark and under illumination using in situ potential-modulated absorption spectroscopy (PMAS) and light-modulated absorption spectroscopy (LMAS) combined with impedance spectroscopy. Formation of surface-bound higher-valent iron species (or "surface trapped holes") was deduced from the PMAS spectra measured in the OER onset region. Similar LMAS spectra were obtained at more negative potentials in the onset region of photoelectrochemical OER, indicating involvement of the same intermediates. The impedance response of the mesoporous α-Fe 2O 3 electrodes exhibits characteristic transmission line behavior that is attributed to slow hopping of holes, probably between surface iron species. Frequency-resolved PMAS and LMAS measurements revealed slow relaxation behavior that can be related to the impedance response and that indicates that the lifetime of the intermediates (or trapped holes) involved in the OER is remarkably long.

    Details

    Item Type Articles
    CreatorsCummings, C. Y., Marken, F., Peter, L. M., Upul Wijayantha, K. G. and Tahir, A. A.
    DOI10.1021/ja209530s
    DepartmentsFaculty of Science > Chemistry
    Publisher StatementPeter_JACS_2012_134_1228.pdf: This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in Journal of the American Chemical Society, copyright © American Chemical Society after peer review. To access the final edited and published work see http://dx.doi.org/10.1021/ja209530s
    RefereedYes
    StatusPublished
    ID Code28889

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