Physicochemical characterization and photoelectrochemical analysis of iron oxide films

Iron oxide films with a nanoporous structure were grown by anodizing sputter-deposited Fe in a fluoride containing ethylene glycol solution and annealed under air exposure at different temperatures. X-ray diffraction and Raman spectroscopy allowed to identify the presence of hematite and/or magnetite after thermal treatment for films annealed at T≥400 °C under air exposure. According to GDOES compositional depth profiles, the thermal treatment sensitively reduced the amount of fluoride species incorporated into the film during the anodizing process. A band gap value of ∼2.0 eV was estimated for all the investigated layers, while a flat band potential dependent on both the growth conditions as well as on the annealing temperature was estimated.