Investigation of oxygen vacancies in Ce coupled TiO ₂ nanocomposites by Raman and PL spectra

Abstract

CeO2–TiO2 nanocomposites with different Ce weight percentages (2, 4, 6 and 8%) were synthesized by sol-gel method. The influence of cerium inclusion on the structural, morphological, optical properties and elemental composition has been analyzed via XRD, BET surface area analysis, UV-DRS, HR-SEM, EDAX, TEM, Raman and photoluminescence spectra. The structural study showed that all the CeO2–TiO2 nanocomposites crystallized in tetragonal structure with anatase phase. Morphological study revealed that the nanocomposites are in spherical shape with size between 13–15 nm. Raman and PL spectra confirmed the presence and influence of oxygen vacancy defects. The adsorption ability of the CeO2–TiO2 nanocomposites was investigated for congo red dye under dark condition. CeO2–TiO2 nanocomposites have enhanced adsorptive performance in comparison with bare TiO2 nanoparticles. The enhanced adsorptive activity of CeO2–TiO2 nanocomposites is due to the higher surface area of the nanocomposites and oxygen vacancies present in the surface of the nanocomposites. The pseudo second order kinetic equation fits well with higher correlation coefficient compared to the pseudo first order in explaining the reaction kinetics.

Synthesis of W‐doped TiO2 by low‐temperature hydrolysis: Effects of annealing temperature and doping content on the surface microstructure and photocatalytic activity

“…More specifically, the anatase modes (A 1g + B 1g + 3E g ) appear at 143, 196, 396, 514, and 638 cm −1 , [32] while the rutile modes (A 1g + E g ) are observed at 446 and 608 cm −1 . [33] Although the shifting indicates an expansion of the unit cell dimensions of doped TiO 2 . While there is a broadening and shifting toward higher wavenumbers by increasing the percentage of doping.…”

“…The broadening is due to the generation of oxygen vacancies by the displacement of oxide ions from their normal lattice. [33] Although the shifting indicates an expansion of the unit cell dimensions of doped TiO 2 . The shift in the E g peak increases linearly with increasing tungsten concentration and is consistent with formation of a solid solution as observed by the XRD data for the sample 5W-900.…”

Surfactant modulated structural modification of hybrid poly(p-phenylenediamine)/titanium dioxide composites and investigation of their functional behaviour

“…The strong emission band at 455 nm is due to the defects on the surfaces of composites. It is reported that the green emission of the TiO 2 composites results from the surface defects formed by oxygen vacancies or the Ti interstitials on the composite surface [35].…”

Visible Light Photodegradation of Formaldehyde over TiO2 Nanotubes Synthesized via Electrochemical Anodization of Titanium Foil

“…Furthermore, the intensity variations suggest that the PL spectrum of TiO2 NTs with larger crystallite size is dominated by a radiative recombination of electrons via intrinsic defects states. The blue emission is visible due to the available surface energy that induces quantum confinement effect and also due to the presence of oxygen vacancies defects on the surface of TiO2 [56]. The bandgap values obtained from the PL spectrum are shown in Table 1.…”

“…The PL peak intensities of the as-synthesized TiO 2 NTs showed a significant decrease compared to those calcined at 350, 450, and 550 • C. Furthermore, the intensity variations suggest that the PL spectrum of TiO 2 NTs with larger crystallite size is dominated by a radiative recombination of electrons via intrinsic defects states. The blue emission is visible due to the available surface energy that induces quantum confinement effect and also due to the presence of oxygen vacancies defects on the surface of TiO 2 [56].…”