Defect‐mediated optical properties of Fe‐substituted TiO ₂ nanoparticles

Abstract Here, sol–gel derived Fe–TiO ₂ anatase nanoparticles with varying concentrations of Ti _{(1– x )} Fe _x O ₂ ( x = 0%, 1%, 5%, 10%) were prepared. The structural, morphological, and optical properties of prepared samples were studied. X‐ray diffraction (XRD) patterns show the formation of pure anatase phase. The mean crystallite size of Fe–TiO ₂ decreases with increase in the concentration of Fe. Fourier transform infrared spectroscopy (FTIR) spectra confirmed the presence of Ti–O vibrational band for all the samples. In Raman spectrum, peak broadening and red shifting linked with Eg ∼144 cm ^–1 divulge the Fe substitution at Ti sites into host lattice structure. Photoluminescence (PL) spectra verified nine peaks related to near band‐edge emission and various defect states. The UV–vis diffuse reflectance spectra represent redshift and reduction in the bandgap energy. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) investigations show that the size of the grains decreases with increase in Fe doping concentration. The study shows that Fe‐doped TiO ₂ anatase phase nanoparticles are suitable for photocatalytic activity and solar cell applications.