Water-Based Sol–Gel Synthesis of Ce-Doped TiO2 Nanoparticles

Abstract

Pure titanium dioxide (TiO2) and Ce-doped TiO2 nanoparticles (NPs) were synthesized with the different dopant percentages of 2%, 4%, 6%, 8%, and 10% by using titanium tetrachloride (TiCl4) and cerium chloride (CeCl3) precursors, pure water as a solvent, and hydrochloric acid (HCl) as the hydrolysis reactor in the presence of ethylene glycol (C4H10O3) stabilizer through the sol–gel method. The morphological, structural, optical and electronic properties of the NPs were investigated via x-ray diffraction (XRD) analysis, field emission scanning electron microscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS) and photoluminescence spectroscopy (PL). From the XRD analysis, it was found that the structure of the Ce-TiO2 NPs remained unchanged in the tetragonal state and anatase phase by increasing dopant, while the size of the nanocrystals (29 nm) in the pure state decreased down to 25 nm by increasing dopant up to 6%. The apparent pseudo-spherical shape and diameter of about 26 nm were obtained for the impure NPs through TEM. The UV-DRS analysis indicated the wide-band gap formation of the NPs through the water-based sol–gel method. As Ce increased, the band gap was enhanced from 5.02 eV for the pure TiO2 NPs up to 5.46 eV for the NPs of 10% dopant. The wide band gap created in these NPs allowed them to be used with an optimum absorption in the ultraviolet (UV) light applications. The results of FTIR analysis showed that the absorption peak of 508 cm−1 was related to the vibrational bond of Ti-O-Ce in the pure state, which changed towards the frequencies of 498 cm−1, 513 cm−1, 490 cm−1, 492 cm−1 and 469 cm−1 for the Ce dopant concentrations of 2%, 4%, 6%, 8%, and 10% entering into the TiO2 matrix, respectively. Finally, the results of the PL analysis revealed that the maximum energy-band interaction of TiO2 with Ce was created at 426 nm with a dopant of 6%.