Photoelectrochemical Performance of Nanotubular Fe₂O₃-TiO₂ Electrodes under Solar Radiation

Fe₂O₃-TiO₂ materials were obtained by the cathodic electrochemical deposition of Fe on anodic TiO₂ at different deposition times (5-180 s), followed by annealing at 450 °C. The effect of the hematite content on the photoelectrochemical (PEC) activity of the received materials was studied. The synthesized electrodes were characterized by field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Raman spectroscopy, diffuse reflectance spectroscopy (DRS), Mott-Schottky analysis, and PEC measurements. It was shown that the amount of deposited iron (ca. 0.5 at.%-30 at.%) and, consequently, hematite after a final annealing increased with the extension of deposition time and directly affected the semiconducting properties of the hybrid material. It was observed that the flat band potential shifted towards more positive values, facilitating photoelectrochemical water oxidation. In addition, the optical band gap decreased from 3.18 eV to 2.77 eV, which resulted in enhanced PEC visible-light response. Moreover, the Fe₂O₃-TiO₂ electrodes were sensitive to the addition of glucose, which indicates that such materials may be considered as potential PEC sensors for the detection of glucose.