Sol–Gel Synthesis of Fe-Doped TiO2 Nanocrystals

Abstract

Fe-doped TiO2 powders were synthesized by the sol–gel method using titanium
(IV) isopropoxide (TTIP) as the starting material, ethanol as solvent, and
ethylene glycol (EG) as stabilizer. These prepared samples were characterized
by x-ray diffractometer (XRD), field emission scanning electron microscope
(FESEM), Fourier-transform infrared (FTIR) spectroscopy, diffuse reflection
spectroscopy (DRS), energy-dispersive x-ray spectroscopy (EDX), and photoluminescence
(PL) analyses to study their structure, morphology, and optical
properties. The particle size of Fe-doped TiO2 was in the range of 18–39 nm
and the minimum crystallite size was achieved for 4 mol.% of Fe. The XRD
result of the samples that were doped with Fe showed a tetragonal structure.
It also revealed the coexistence of the anatase and rutile phases, and showed
that their ratio changed with various molar concentrations of Fe dopant. FTIR
spectroscopy showed the presence of the Ti-O vibration band in the samples.
PL analysis revealed the PL property in the UV region. Visible irradiation and
the intensity of PL spectra were both reduced by doping TiO2 with 3 mol.% of
Fe as compared to the pure variety. The spectra from the DRS showed a red
shift and a reduction of 2.6 eV in the band gap energy for 4 mol.% Fe-doped
TiO2. The optimum level of impurity (4 mol.%) for Fe-doped TiO2 nanoparticles
(NPs), which improve the optical and electrical properties by using new
precursors and can be used in solar cells and electronic devices, was determined.
The novelty of this work consists of: the Fe/TiO2 NPs are synthesized
by new precursors from sol–gel synthesis of iron and TTIP using acetic acidcatalyzed
solvolysis (original idea) and the optical properties optimized with a
mixture of phases (anatase/rutile) of Fe-doped TiO2 by this facile method.