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Issue 44, 2015
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Improvement of the electron collection efficiency in porous hematite using a thin iron oxide underlayer: towards efficient all-iron based photoelectrodes

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Abstract

Different approaches have been explored to increase the water oxidation activity of nanostructured hematite (α-Fe2O3) photoanodes, including doping with various elements, surface functionalization with both oxygen evolving catalysts (OEC) and functional overlayers and, more recently, the introduction of ultrathin oxide underlayers as tunneling back contacts. Inspired by this latter strategy, we present here a photoanode design with a nanometric spin-coated iron oxide underlayer coupled with a mesoporous hematite film deposited by electrophoresis. The electrodes equipped with the thin underlayer exhibit a four-fold improvement in photoactivity over the simple hematite porous film, reaching a stable photocurrent density of ca. 1 mA cm−2 at 0.65 V versus the saturated calomel electrode (SCE) at pH 13.3 (NaOH 0.1 M) under air mass (AM) 1.5G illumination. A further improvement to 1.5 mA cm−2 is observed after decoration of the hematite surface with a Fe(III)-OEC. These results demonstrate that by combining different iron oxide morphologies, it is possible to improve the selectivity of the interfaces towards both electron collection at the back contact and hole transfer to the electrolyte, obtaining an efficient all-iron based photoelectrode entirely realized with simple wet solution scalable procedures.

Graphical abstract: Improvement of the electron collection efficiency in porous hematite using a thin iron oxide underlayer: towards efficient all-iron based photoelectrodes

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Publication details

The article was received on 15 Jul 2015, accepted on 05 Oct 2015 and first published on 19 Oct 2015


Article type: Paper
DOI: 10.1039/C5CP04152J
Citation: Phys. Chem. Chem. Phys., 2015,17, 29661-29670
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    Improvement of the electron collection efficiency in porous hematite using a thin iron oxide underlayer: towards efficient all-iron based photoelectrodes

    N. Dalle Carbonare, S. Carli, R. Argazzi, M. Orlandi, N. Bazzanella, A. Miotello, S. Caramori and C. A. Bignozzi, Phys. Chem. Chem. Phys., 2015, 17, 29661
    DOI: 10.1039/C5CP04152J

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