Water oxidation at hematite photoelectrodes: the role of surface states
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Título
Water oxidation at hematite photoelectrodes: the role of surface statesAutoría
Fecha de publicación
2012Editor
American Chemical SocietyISSN
0002-7863Tipo de documento
info:eu-repo/semantics/articleVersión de la editorial
http://pubs.acs.org/doi/abs/10.1021%2Fja210755hVersión
info:eu-repo/semantics/submittedVersionPalabras clave / Materias
Resumen
Hematite (α-Fe2O3) constitutes one of the most promising semiconductor materials for the conversion of sunlight into chemical fuels by water splitting. Its inherent drawbacks related to the long penetration depth of ... [+]
Hematite (α-Fe2O3) constitutes one of the most promising semiconductor materials for the conversion of sunlight into chemical fuels by water splitting. Its inherent drawbacks related to the long penetration depth of light and poor charge carrier conductivity are being progressively overcome by employing nanostructuring strategies and improved catalysts. However, the physical–chemical mechanisms responsible for the photoelectrochemical performance of this material (J(V) response) are still poorly understood. In the present study we prepared thin film hematite electrodes by atomic layer deposition to study the photoelectrochemical properties of this material under water-splitting conditions. We employed impedance spectroscopy to determine the main steps involved in photocurrent production at different conditions of voltage, light intensity, and electrolyte pH. A general physical model is proposed, which includes the existence of a surface state at the semiconductor/liquid interface where holes accumulate. The strong correlation between the charging of this state with the charge transfer resistance and the photocurrent onset provides new evidence of the accumulation of holes in surface states at the semiconductor/electrolyte interface, which are responsible for water oxidation. The charging of this surface state under illumination is also related to the shift of the measured flat-band potential. These findings demonstrate the utility of impedance spectroscopy in investigations of hematite electrodes to provide key parameters of photoelectrodes with a relatively simple measurement. [-]
Publicado en
Journal of the American Chemical Society, 134, 9Derechos de acceso
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.
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info:eu-repo/semantics/openAccess
http://rightsstatements.org/vocab/InC/1.0/
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