Characterization of structured α-Fe2O3 photoanodes prepared via electrodeposition and thermal oxidation of iron

In this paper we explore the feasibility of using electrodeposition as a low-cost, versatile and easily upscalable technique for preparing alpha-Fe2O3 (hematite) photoanodes for water splitting applications. The photoelectrodes are prepared on transparent conducting glass substrates by electrodeposition of Fe, using a nonaqueous precursor solution at room temperature, followed by thermal oxidation in air. Variations in deposition parameters yield films with diverse morphologies. The effects of the different morphologies on the structural, optical, and photoelectrochemical properties are investigated by photocurrent measurements under AM1.5 illumination. The photocurrent could be improved by growing the first part of the Fe film at low current densities, yielding a dense underlayer, followed by the deposition of a more structured, porous film at high current densities. X-ray diffraction reveals that high deposition currents result in smaller crystallites and a (110) preferred orientation. This orientation is favorable when using hematite as a photoanode, since the conductivity in the [110] direction is known to be up to four orders of magnitude higher than in directions perpendicular to this. (C) 2011 Elsevier B.V. All rights reserved.