Effects of slight Fe (III)-doping on structural and optical properties of TiO2 nanoparticles

In this research work, undoped and slight Fe-doped-TiO2 nanoparticles (Fe–TiO2 NPs) were prepared using simple chemical sol–gel method and post-annealing temperature at 550 °C. This method is less expensive, and can be easily implemented. The samples were prepared using titanium (IV) isopropoxide (TTIP) as precursor, and iron sulfate hypetahydrate (FeSO4·7H2O) as doping sources. The crystalline structure, morphological, and optical proprieties were obtained using X-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDX), and UV–Vis in mode diffuse reflectance spectroscopy (DRS). XRD result of Fe-doped samples showed a tetragonal structure and the presence of anatase–rutile mixed phase of TiO2. Fe (III) can be easily incorporated in the TiO2 lattice without disturbing the tetragonal system of TiO2. Analysis by UV–Vis in DRS mode reveals improvement in absorption efficiency in the visible range for Fe-doped TiO2. The nanoparticles formation is confirmed by SEM images. These nanoparticles can be used as photoanode in solar cells and photocatalytic activity. Our results show that doping with 1% Fe significantly improved the efficiency of the photo-absorption resulting in the visible shift. This shift is connected to the decrease in TiO2 band gap as measured by using Kabelka–Munk function F(R) and confirmed by the values of Urbach energy. Moreover, the prepared Fe-doped TiO2 samples containing mixtures of anatase and rutile nanoparticles with appropriate proportions, which can be used in solar cell application.