Characterization and optical properties of mechanochemically synthesized molybdenum-doped rutile nanoparticles and their electronic structure studies by density functional theory

• Published in: Materials today chemistry Vol. 24; p. 100820
• Main Authors: Maleki-Ghaleh, H., Shakeri, M.S., Dargahi, Z., Kavanlouei, M., Kaveh Garabagh, H., Moradpur-Tari, E., Yourdkhani, A., Fallah, A., Zarrabi, A., Koc, B., Siadati, M.H.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-06-2022
• Subjects: DFT simulation; Electronic band structure; Mechanochemical synthesis; Molybdenum doping; Optical properties; Rutile TiO2; Rutile TiO2; DFT simulation; Optical properties; Electronic band structure; Molybdenum doping; Mechanochemical synthesis
• ISSN: 2468-5194; 2468-5194
• DOI: 10.1016/j.mtchem.2022.100820

The optical and electronic properties of molybdenum (Mo) doped rutile TiO2 prepared by the mechanochemical method were studied both experimentally and using density functional theory (DFT). The synthesized nanoparticles were characterized by XRD, TEM, EDS-MAP, and XPS. The XRD results showed the successful incorporation of Mo in the rutile crystal lattice. High-resolution TEM images illustrated a decreasing trend in the (110) d-spacing for samples doped up to 3 at%. The shift toward higher binding energies in the XPS spectra was due to the higher oxidization tendencies of Mo5+ and Mo6+ substituted in Ti4+ sites. The optical behavior of samples was examined by UV–Vis and photoluminescence spectroscopy. The bandgap energy value of rutile was reduced from 3.0 eV to 2.4 eV by 2 at% Mo doping. The DFT calculations showed a reduction of bandgap energy value of rutile to 2.35 eV with 2 at% Mo, which is in harmony with the experimental results. The creation of energy states below the conduction band because of Mo doping was identified as the reason for reducing the bandgap energy and photoluminescence emission of rutile.
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•Mo doping in rutile nanoparticles was successfully done by the mechanochemical method.•The d-spacing of rutile crystallographic planes reduced with Mo doping.•Mo doping increased the oxidization tendency of the rutile atoms due to the substitution of Mo5+ and Mo6+ in place of Ti4+.•The bandgap of rutile decreased from 3 to 2.4 eV in the optimal sample; 2 at% Mo doping.•Creation of Mo 4d energy states below the conduction band of rutile caused its bandgap reduction.