Pseudobrookite (Fe2TiO5) films: Synthesis, properties and photoelectrochemical characterization

• Published in: Catalysis today Vol. 413-415; p. 113982
• Main Authors: Imrich, Tomáš, Krýsová, Hana, Neumann-Spallart, Michael, Krýsa, Josef
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-03-2023
• Subjects: Photoelectrochemistry; Pseudobrookite; Spray pyrolysis; Photoelectrochemistry; Pseudobrookite; Spray pyrolysis
• ISSN: 0920-5861; 1873-4308
• DOI: 10.1016/j.cattod.2022.12.013

Pseudobrookite, Fe2TiO5, precursor films were obtained by spray pyrolysis (SP) at 550 °C on fused silica and FTO (F-doped tin oxide on borosilicate glass) using iron (III) acetylacetonate (FeAcAc) and titanium diisopropoxide bis(acetylacetonate) (DIPTiAcAc) in methanol. SP was followed by annealing in air from 600 °C to 1000 °C for various durations, and for T ≥ 750 °C, phase pure pseudobrookite was obtained. (Photo)electrochemical experiments of Fe2TiO5 electrodes in junctions with aqueous electrolytes showed n-type behaviour of the material with a maximum photocurrent of 0.35 mA/cm2 under simulated AM1.5 sunlight. A valence band energy between 6.6 and 6.8 eV was estimated using the electrochemical results. The position of the Fe2TiO5 valence band enables the passage of (photogenerated) holes in hematite into a pseudobrookite layer and further on towards an electrolyte, if a hematite/pseudobrookite stratified film would be applied in a solid / liquid junction. The valence band potential is not positive enough for producing OH· radicals, only solvent oxidation and reactions which do not require OH· radicals can proceed.
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•Fe2TiO5 precursor films were synthetized by spray pyrolysis on fused silica and FTO.•For obtaining phase pure material, annealing in air for 60 h at temperature ≥ 750 °C was necessary.•Fe2TiO5 showed n-type behaviour with a photocurrent of 0.35 mA/cm2 (1 sun).•The position of the valence band enables the passage of holes from hematite into Fe2TiO5.