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Royal Society of Chemistry, Physical Chemistry Chemical Physics, 38(14), p. 13224, 2012

DOI: 10.1039/c2cp42535a

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Mesoporous α-Fe2O3 thin films synthesized via the sol–gel process for light-driven water oxidation

This paper was not found in any repository, but could be made available legally by the author.
This paper was not found in any repository, but could be made available legally by the author.

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Abstract

This work reports a facile and cost-effective method for synthesizing photoactive alpha-Fe2O3 films as well as their performances when used as photoanodes for water oxidation. Transparent alpha-Fe2O3 mesoporous films were fabricated by template-directed sol-gel chemistry coupled with the dip-coating approach, followed by annealing at various temperatures from 350 degrees C to 750 degrees C in air. alpha-Fe2O3 films were characterized by X-ray diffraction, XPS, FE-SEM and electrochemical measurements. The photoelectrochemical performance of alpha-Fe2O3 photoanodes was characterized and optimized through the deposition of Co-based co-catalysts via different methods (impregnation, electro-deposition and photo-electro-deposition). Interestingly, the resulting hematite films heat-treated at relatively low temperature (500 degrees C), and therefore devoid of any extrinsic dopant, achieve light-driven water oxidation under near-to-neutral (pH = 8) aqueous conditions after decoration with a Co catalyst. The onset potential is 0.75 V vs. the reversible hydrogen electrode (RHE), thus corresponding to 450 mV light-induced underpotential, although modest photocurrent density values (40 mu A cm(-2)) are obtained below 1.23 V vs. RHE. These new materials with a very large interfacial area in contact with the electrolyte and allowing for a high loading of water oxidation catalysts open new avenues for the optimization of photo-electrochemical water