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Issue 19, 2014
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Hydrogen-treated hematite nanostructures with low onset potential for highly efficient solar water oxidation

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Abstract

Hydrogen-treated hematite nanostructures were prepared by a simple pyrolysis of NaBH4 in a crucible. The H2-treated hematite photoelectrode showed high efficiency for solar water oxidation with a photocurrent of 2.28 mA cm−2 at 1.23 V vs. RHE, which was over 2.5 times higher than that for pristine hematite (0.88 mA cm−2). The significant improvement of the photocurrent can be attributed to increased oxygen vacancies after the H2 treatment. Moreover, the onset potential for H2-treated hematite was low and when compared to the hematite photoelectrode treated in an oxygen-deficient atmosphere to produce oxygen vacancies, a cathodic shift of the onset potential was observed by about 120 mV (from 0.99 to 0.87 V vs. RHE). The cathodic shift of the onset potential was attributed to the surface effect of H2 treatment while the oxygen-deficiency treatment mainly affected the bulk, which was confirmed by X-ray absorption spectroscopy. The results also suggest that the presence of surface defect states of Fe2+ in hematite is not the reason for high onset potential described in the literature. The H2-treated hematite with high efficiency could be used as a good starting material to achieve better performance for practical applications with further modifications such as surface catalysts or elemental doping.

Graphical abstract: Hydrogen-treated hematite nanostructures with low onset potential for highly efficient solar water oxidation

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Publication details

The article was received on 11 Feb 2014, accepted on 06 Mar 2014 and first published on 07 Mar 2014


Article type: Paper
DOI: 10.1039/C4TA00729H
J. Mater. Chem. A, 2014,2, 6727-6733

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    Hydrogen-treated hematite nanostructures with low onset potential for highly efficient solar water oxidation

    M. Li, J. Deng, A. Pu, P. Zhang, H. Zhang, J. Gao, Y. Hao, J. Zhong and X. Sun, J. Mater. Chem. A, 2014, 2, 6727
    DOI: 10.1039/C4TA00729H

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