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

Pseudobrookite, Fe2TiO5, precursor films were obtained by spray pyrolysis (SP) at 550 degrees 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 degrees C to 1000 degrees C for various durations, and for T >= 750 degrees 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/cm(2) 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 center dot radicals, only solvent oxidation and reactions which do not require OH center dot radicals can proceed.

Automated summary

In this study, precursor films of pseudobrookite, Fe2TiO5, were obtained using spray pyrolysis technique. By annealing at high temperatures, phase-pure pseudobrookite films were obtained. Electrochemical experiments showed that Fe2TiO5 electrodes exhibited n-type behavior with a maximum photocurrent of 0.35 mA/cm(2) under simulated sunlight. The valence band energy of Fe2TiO5 was estimated to be between 6.6 and 6.8 eV.